Sir Peter John Ratcliffe, FRS, FMedSci (born 14 May 1954) is a British Nobel Laureate physician-scientist who is trained as a nephrologist. He was a practising clinician at the John Radcliffe Hospital, Oxford and Nuffield Professor of Clinical Medicine and head of the Nuffield Department of Clinical Medicine at the University of Oxford from 2004 to 2016. In 2016 he became Clinical Research Director at the Francis Crick Institute, retaining a position at Oxford as member of the Ludwig Institute of Cancer Research and Director of the Target Discovery Institute, University of Oxford.
Ratcliffe is best known for his work on cellular reactions to hypoxia, for which he shared the 2019 Nobel Prize in Physiology or Medicine with William Kaelin Jr. and Gregg L. Semenza.
Ratcliffe was born in Lancashire on 14 May 1954, to William Ratcliffe and Alice Margaret Ratcliffe. He attended Lancaster Royal Grammar School from 1965 to 1972.
He won an open scholarship to Gonville and Caius College, Cambridge in 1972 to study Medicine at the University of Cambridge and then completed his MB BChir medical degree with distinction at St Bartholomew's Hospital Medical College in 1978.
Ratcliffe then trained in renal medicine at Oxford University, focusing on renal oxygenation. He earned a higher MD degree from University of Cambridge in 1987.