If you consider my situation: a guy who comes back from arguably, you know, a death sentence [i.e., Armstrong's 1996 cancer diagnosis and treatment], why would I then enter into a sport and dope myself up and risk my life again? That's crazy. I would never do that. No. No way.
— Lance Armstrong, 2005
Armstrong has been criticized for his disagreements with outspoken opponents of
doping such as
 Bassons wrote a number of articles for a French newspaper during the
1999 Tour de France which made references to doping in the
peloton. Subsequently, Armstrong had an altercation with Bassons during the 1999 Tour de France where Bassons said Armstrong rode up alongside on the Alpe d'Huez stage to tell him "it was a mistake to speak out the way I (Bassons) do and he (Armstrong) asked why I was doing it. I told him that I'm thinking of the next generation of riders. Then he said 'Why don't you leave, then?'"
Armstrong later confirmed Bassons's story. On the main evening news on
TF1, a French television station, Armstrong said: "His accusations aren't good for cycling, for his team, for me, for anybody. If he thinks cycling works like that, he's wrong and he would be better off going home".
 Kimmage, a professional cyclist in the 1980s who later became a sports journalist, referred to Armstrong as a "cancer in cycling".
 He also asked Armstrong questions in relation to his "admiration for dopers" at a press conference at the Tour of California in 2009, provoking a scathing reaction from Armstrong.
 This spat continued and is exemplified by Kimmage's articles in
The Sunday Times.
Another notable critic of Armstrong was
David Walsh, also a reporter for The Sunday Times.
 Referred to as a "little troll" by Armstrong, Walsh revealed in a 2001 Sunday Times story that he had ties to controversial Italian doctor
Michele Ferrari. Two years later, Walsh's book L.A. Confidentiel alleged, based on testimony by Armstrong's former
masseuse Emma O'Reilly, that clandestine trips were made to pick up and deliver doping products to Armstrong's team.
Until his 2013 admission, Armstrong continually denied using illegal performance-enhancing drugs and described himself as the most tested athlete in the world.
 However, a 1999 urine sample showed traces of
corticosteroid; a medical certificate showed he used an approved cream for
saddle sores which contained the substance.
 O'Reilly claimed that team officials conspired with a compliant doctor to falsify Armstrong's prescription, and that Armstrong never had the condition.
 She also claimed that, on other occasions, she was asked to dispose of used syringes for Armstrong and pick up strange parcels for the team.
From his return to cycling in the fall of 2008 through March 2009, Armstrong submitted to twenty-four unannounced drug tests by various anti-doping authorities. All of the tests were negative for performance-enhancing drugs.
U.S. federal prosecutors pursued allegations of doping by Armstrong from 2010–2012. The effort convened a
grand jury to investigate doping charges, including taking statements under oath from Armstrong's former team members and other associates; met with officials from France, Belgium, Spain, and Italy; and requested samples from the
French anti-doping agency. The investigation was led by federal agent
Jeff Novitzky, who also investigated suspicions of steroid use by baseball players
Barry Bonds and
Roger Clemens. The probe was terminated on February 3, 2012 with no charges filed.
Tyler Hamilton, a professional cyclist who rode as Lance Armstrong's principal
Domestique on the U.S. Postal Cycling team from 1999 through 2001, has extensively documented the history and methods of doping by Armstrong, himself, and others in "The Secret Race", a book co-authored with Daniel Coyle and published in 2012. The book also describes the investigation by
Jeff Novitzky and the
Food and Drug Administration and Hamilton's befuddlement that the investigation was dropped.
Armstrong faced accusations of doping as early as the
1999 Tour de France. Specifically, many European papers contended his victory in Stage 9, in which he seemingly ascended the Alps with almost no difficulty, could not have been possible through natural means. Armstrong adamantly denied this, and the American press generally supported him. Armstrong contended, among other things, that it would have made no sense for him to dope since he lived in France for most of the year; France has some of the strictest anti-doping laws in the world.
Armstrong was criticized for working with controversial Italian trainer Michele Ferrari. Ferrari claimed that he was introduced to Lance by
Eddy Merckx in 1995.
Greg LeMond described himself as "devastated" on hearing of them working together, while
Tour de France organizer
Jean-Marie Leblanc said, "I am not happy the two names are mixed."
 Following Ferrari's later-overturned conviction for "sporting fraud" and "abuse of the medical profession", Armstrong suspended his professional relationship with him, saying that he had "zero tolerance for anyone convicted of using or facilitating the use of performance-enhancing drugs" and denying that Ferrari had ever "suggested, prescribed or provided me with any performance-enhancing drugs."
Ferrari was later absolved of all charges by an Italian appeals court of the sporting fraud charges as well as charges of abusing his medical license to write prescriptions. The court stated that it overturned his conviction "because the facts do not exist" to support the charges.
 Ferrari, however, is still banned from practicing medicine with cyclists by the
Italian Cycling Federation. According to Italian authorities, Armstrong met with Ferrari as recently as 2010 in a country outside of Italy.
In 2004, Walsh and fellow reporter
Pierre Ballester published a French-language book alleging Armstrong had used performance-enhancing drugs, entitled
L. A. Confidentiel – Les secrets de Lance Armstrong. The book contains allegations by Emma O'Reilly that Armstrong once asked her to dispose of used syringes and to give him makeup to conceal needle marks on his arms. Another figure in the book,
Steve Swart, claims he and other riders, including Armstrong, began using drugs in 1995 while members of the
Motorola team, a claim denied by other team members.
Allegations in the book were reprinted in the British newspaper
The Sunday Times in a story by deputy sports editor Alan English in June 2004. Armstrong sued for
libel, and the paper settled out of court after a
High Court judge in a pre-trial ruling stated that the article "meant accusation of guilt and not simply reasonable grounds to suspect."
 The newspaper's lawyers stated, "The Sunday Times has confirmed to Mr. Armstrong that it never intended to accuse him of being guilty of taking any performance-enhancing drugs and sincerely apologized for any such impression."
 Ballester and Walsh subsequently published L.A. Official and Le Sale Tour (The Dirty Trick), further pressing their claims that Armstrong used performance-enhancing drugs throughout his career.
On March 31, 2005, Mike Anderson filed a brief
 in Travis County District Court in
Texas, as part of a legal battle following his termination in November 2004 as an employee of Armstrong. Anderson worked for Armstrong for two years as a personal assistant. In the brief, Anderson claimed that he discovered a box of
androstenone while cleaning a bathroom in Armstrong's apartment in
 Androstenone is not on the list of banned drugs. Anderson stated in a subsequent deposition that he had no direct knowledge of Armstrong using a banned substance. Armstrong denied the claim and issued a counter-suit.
 The two men reached an out-of-court settlement in November 2005; the terms of the agreement were not disclosed.
In June 2006, French newspaper
Le Monde reported claims by Betsy and
Frankie Andreu during a deposition that Armstrong had admitted using performance-enhancing drugs to his physician just after brain surgery in 1996. The Andreus' testimony was related to litigation between Armstrong and SCA Promotions, a Texas insurer who balked at paying a $5 million bonus for Armstrong's sixth Tour victory due to the claims raised in L. A. Confidentiel. This was settled out of court with SCA paying Armstrong and Tailwind Sports $7.5 million, to cover the $5-million bonus plus interest and lawyers' fees. Betsy Andreu's testimony stated, "And so the doctor asked him a few questions, not many, and then one of the questions he asked was... have you ever used any performance-enhancing drugs? And Lance said yes. And the doctor asked, what were they? And Lance said,
Armstrong suggested Betsy Andreu may have been confused by possible mention of his post-operative treatment which included steroids and EPO that are taken to counteract wasting and red-blood-cell-destroying effects of intensive
 The Andreus' allegation was not supported by the eight other people present, including Armstrong's doctor Craig Nichols,
 or his medical history. According to Greg LeMond, he had recorded a conversation,
 transcribed for review by
National Public Radio, in which Armstrong's contact at Oaklety, Inc., Stephanie McIlvain, corroborated Betsy Andreu's account. However, McIlvain contradicted LeMond's allegations and denied under oath that the incident ever occurred.
In July 2006, the
Los Angeles Times published a story on the allegations raised in the SCA case.
 The report cited evidence at the trial including the results of the LNDD test and an analysis of these results by an expert witness.
 According to the Times, Australian researcher Michael Ashenden testified that Armstrong's levels rose and fell, consistent with a series of injections during the 1999 Tour. Ashenden, a paid expert retained by SCA Promotions, told arbitrators the results painted a "compelling picture" that the world's most famous cyclist "used EPO in the '99 Tour."
SCA president Bob Hamman knew his chances of winning the suit were slim, since the language in SCA's contract with Armstrong stipulated that the money had to be paid. However, he believed that the testimony and evidence would prove that Armstrong was a doper, and would be enough to trigger an investigation by sporting authorities. His hunch proved right; before the Times ran its story on the case,
United States Anti-Doping Agency general counsel
Travis Tygart contacted Hamman and asked to see the evidence he'd gleaned.
Ashenden's findings were disputed by the Vrijman report, which pointed to procedural and privacy issues in dismissing the LNDD test results. The Los Angeles Times article also provided information on testimony given by Swart, the Andreus, and an
instant messaging conversation between Frankie Andreu and
Jonathan Vaughters regarding blood-doping in the peloton. Vaughters signed a statement disavowing the comments and stating he had "no personal knowledge that any team in the Tour de France, including Armstrong's Discovery team in 2005, engaged in any prohibited conduct whatsoever." Andreu signed a statement affirming the conversation took place as indicated on the instant messaging logs submitted to the court.
 The SCA trial was settled out of court, and while no verdict or finding of facts was rendered, Armstrong regarded the outcome as proof that the doping allegations were baseless.
On May 20, 2010, former U.S. Postal teammate
Floyd Landis – who had previously been stripped of the 2006 Tour de France title after a positive drug test – accused Armstrong of doping in 2002 and 2003.
 Landis also claimed that U.S. Postal team director Johan Bruyneel had bribed former
Hein Verbruggen to keep quiet about a positive Armstrong test in 2002.
 Landis admitted there was no documentation supporting his claims.
 However, in July 2010 the president of the UCI, Pat McQuaid, revealed that Armstrong made two donations to the UCI: $25,000 in 2002, used by the juniors anti-doping program, and $100,000 in 2005, to buy a blood testing machine, and documentation of those payments did exist.
Landis also maintained that he witnessed Armstrong receiving multiple blood transfusions, and dispensing testosterone patches to his teammates.
 On May 25, 2010, the UCI disputed Landis's claims, insisting that "none of the tests revealed the presence of EPO in the samples taken from riders at the 2001 Tour of Switzerland." According to ESPN, "Landis claimed that Armstrong tested positive while winning in 2002, a timeline Armstrong himself said left him 'confused,' because he did not compete in the event in 2002."
In May 2011, former Armstrong teammate
Tyler Hamilton told
CBS News that he and Armstrong had together taken EPO before and during the 1999, 2000, and 2001 Tours de France. Armstrong's attorney, Mark Fabiani, responded that Hamilton was lying.
 The accompanying
60 Minutes investigation alleged that two other former Armstrong teammates,
Frankie Andreu and
George Hincapie, have told federal investigators that they witnessed Armstrong taking banned substances, including EPO, or supplied Armstrong with such substances.
Fabiani stated in response that, "We have no way of knowing what happened in the grand jury and so can't comment on these anonymously sourced reports."
 Hamilton further claimed that Armstrong tested positive for EPO during the 2001
Tour de Suisse; 60 Minutes reported that the
Union Cycliste Internationale intervened to conceal those test results, and that donations from Armstrong totaling US$125,000 may have played into said actions.
Martial Saugy, chief of the Swiss anti-doping agency, later confirmed that they found four urine samples suspicious of EPO use at the 2001 race, but said there was no "positive test" and claimed not to know whether the suspicious results belonged to Armstrong. As a result, Armstrong's lawyers demanded an apology from 60 Minutes.
 Instead of apologizing, CBS News chairman
Jeff Fager said CBS News stands by its report as "truthful, accurate and fair", and added that the suspicious tests which Saugy confirmed to exist have been linked to Armstrong "by a number of international officials".
On February 2, 2012, U.S. federal prosecutors officially dropped their criminal investigation with no charges.
Hardtalk on the
BBC News channel, Hamilton again insisted that he and Armstrong had routinely doped together. Dismissing the fact that Armstrong had passed numerous drug tests, Hamilton said that he himself had also passed hundreds of drug tests while doped.
In the 2012 documentary "The World According to Lance Armstrong",
 the attorney Jeffrey Tillotson states that he thinks the evidence he and his team developed showed that Armstrong had been using performance-enhancing drugs dating back to the beginning of his career. Tillotson was engaged by an insurer that unsuccessfully tried to refuse to pay Armstrong five million USD in bonuses for Armstrongs performance in the Tour de France in 2006, based on their collection of evidence on Armstrong using performance-enhancing drugs.
On October 10, 2012, the U.S. anti-Doping Agency said Armstrong was part of "the most sophisticated, professionalized and successful doping program that sport has ever seen," in advance of issuing its long-awaited report detailing the evidence it acquired.
 In December 2012, Armstrong and his attorney Tim Herman held a secret meeting at the Denver offices of former Colorado governor Bill Ritter, in an attempt to negotiate a reduction of Armstrong's lifetime ban down to one year. But the talks fell apart when Armstrong refused to cooperate with U.S. Anti-Doping Agency CEO Travis Tygart.