The 14 papers in this volume were first presented at the Fifth International Galen Colloqium held in Lille in 1995 and represent a first attempt to explore systematically this vast complicated area. The contributors cover a wide variety of themes, broadly grouped as: the epistemology, method and practice of medicine, Galen and pharmacological tradition, Galen's pharmacological treatises and the transmission of pharmacological texts.Their papers shed a new light on this ancient therapeutic field and also help to understand Galen's pharmacology in its relation to the entire body of its work and thought.