Written in 1199 at the request of al-Qadi al-Fadil, the famous counselor and secretary to Saladin, On Poisons and the Protection against Lethal Drugs is distinguished rabbi Moses Maimonides’ guide to emergency first aid and readily available antidotes. This treatise—assembled from the existing medical literature as well as Maimonides’ own practice—proved highly influential amongst scholars and laypersons in both Jewish and non-Jewish circles alike. Although On Poisons survives in several Arabic and Judeo-Arabic manuscripts, this is the first finished critical edition of the Arabic. The volume also includes critical editions of the medieval Hebrew and Latin translations and a glossary of material medica and technical terms. It will be essential for the shelves of scholars interested in Maimonides and medieval medicine.