Metrodorus was a native of Lampsacus on the Hellespont. His father's name was Athenaeus or Timocrates, his mother's Sande. Together with his brother Timocrates of Lampsacus he joined the school Epicurus had set up in their home town. Timocrates, however, soon fell out with both his brother and Epicurus and devoted the rest of his life to spreading malicious slander about them. Metrodorus on the other hand soon became the most distinguished of the disciples of Epicurus, with whom he lived on terms of the closest friendship, and whom he later followed to Athens, never having left him since he became acquainted with him, except for six months on one occasion, when he paid a visit to his home.
Metrodorus died in 278/7 BC, in the 53rd year of his age, seven years before Epicurus, who would have appointed him his successor had he survived him. He left behind him a son named Epicurus, and a daughter, whom Epicurus, in his will, entrusted to the guardianship of Amynomachus and Timocrates of Potamus, to be brought up under the joint care of themselves and Hermarchus, and provided for out of the property which he left behind him. In a letter also which he wrote upon his death-bed, Epicurus commended the children to the care of Idomeneus, who had married Batis, the sister of Metrodorus. The 20th of each month was kept by the disciples of Epicurus as a festive day in honour of their master and Metrodorus. Leontion is spoken of as the wife or mistress of Metrodorus.
Diogenes mentioned Epicurus letter, "All my books to be given to Hermarchus. And if anything should happen to Hermarchus before the children of Metrodorus grow up, Amynomachus and Timocrates shall give from the funds bequeathed by me, so far as possible, enough for their several needs, as long as they are well ordered. And let them provide for the rest according to my arrangements; that everything may be carried out, so far as it lies in their power. Of my slaves I manumit Mys, Nicias, Lycon, and I also give Phaedrium her liberty."