[Abstract Hitherto, research on Arabic pharmacy and pharmacology has largely been based on the study of pharmacopoeias. While practical in nature, it is not clear to what extent the recipes in the pharmacopoeias were in fact used. The Cairo Genizah, the most famous and best preserved of the many depositories of documents written by medieval Jewish communities, provides us with a unique glimpse of practical medicine, by virtue of the prescriptions found there. These prescriptions reflect the medical reality that actually existed in the eastern Mediterranean basin in the 10th–13th centuries, and will be compared especially to pharmacopoeias known to have been used, or even deriving from, members of the Genizah community, such as Minhāj al-dukkān, al-Dustūr al-bīmāristanī and the works of Maimonides. We will examine three prescriptions in depth, attempting to answer the following questions: Who wrote these prescriptions? Who made them up, i.e. prepared the medical recipes? What can be learnt from the prescriptions about medicine, public/community health, the use of materia medica? To what extent are these prescriptions original, i.e. how do they reflect the relationship between medieval medical theory and practice?, AbstractHitherto, research on Arabic pharmacy and pharmacology has largely been based on the study of pharmacopoeias. While practical in nature, it is not clear to what extent the recipes in the pharmacopoeias were in fact used. The Cairo Genizah, the most famous and best preserved of the many depositories of documents written by medieval Jewish communities, provides us with a unique glimpse of practical medicine, by virtue of the prescriptions found there. These prescriptions reflect the medical reality that actually existed in the eastern Mediterranean basin in the 10th-13th centuries, and will be compared especially to pharmacopoeias known to have been used, or even deriving from, members of the Genizah community, such as Minhāj al-dukkān, al-Dustūr al-bīmāristanī and the works of Maimonides. We will examine three prescriptions in depth, attempting to answer the following questions: Who wrote these prescriptions? Who made them up, i.e. prepared the medical recipes? What can be learnt from the prescriptions about medicine, public/community health, the use of materia medica? To what extent are these prescriptions original, i.e. how do they reflect the relationship between medieval medical theory and practice?]