De Materia Medica (Latin name for the, Peri hules iatrikēs, both meaning "On Medical Material") is a pharmacopoeia of herbs and the medicines that can be obtained from them. The five-volume work describes many drugs known to be effective, including aconite, aloes, colocynth, colchicum, henbane, opium and squill. In all, about 600 plants are covered, along with some animals and mineral substances, and around 1000 medicines made from them.

The work was written between 50 and 70 AD by Pedanius Dioscorides, a Greek physician in the Roman army. It was widely read for more than 1,500 years until supplanted by revised herbals in the Renaissance, making it one of the longest-lasting of all natural history books.

De Materia Medica was circulated as illustrated manuscripts, copied by hand, in Greek, Latin and Arabic throughout the mediaeval period. From the sixteenth century on, Dioscorides' text was translated into Italian, German, Spanish, and French, and in 1655 into English. It formed the basis for herbals in these languages by men such as Leonhart Fuchs, Valerius Cordus, Lobelius, Rembert Dodoens, Carolus Clusius, John Gerard and William Turner. Gradually such herbals included more and more direct observations, supplementing and eventually supplanting the classical text.

Several manuscripts and early printed versions of De Materia Medica survive, including the illustrated Vienna Dioscurides manuscript written in the original Greek in sixth-century Constantinople and used there by the Byzantines as a hospital text for just over a thousand years. Sir Arthur Hill saw a monk on Mount Athos still using a copy of Dioscorides to identify plants in 1934.