This essay analyzes the known evidence for Byzantine engagement with what are conventionally termed "alchemical" texts, theories, and practices of the Islamic world. Much of the evidence is difficult to date. Nevertheless, the aggregated direct, indirect, and circumstantial evidence suggests at least some engagement by Greek-speaking scholars throughout the Middle Ages. This engagement took various forms, from the use of Arabic, Persian, and Turkish terminology to the adaptation of whole Arabic treatises in Greek. Sometimes the Byzantine texts emphasize their Islamicate sources, and sometimes they do not mention these sources at all. The resulting picture is still fragmentary, but it indicates that medieval Greek-speaking scholars were active in the circulation of chemical knowledge and techniques in the Mediterranean and Middle East. Byzantium, therefore, should no longer be left out of research into long-term patterns in the history of science.T he extent to which Byzantine scholars engaged with alchemical texts of the Islamic world is largely unknown. This is due in the first place to the infancy in which research on Byzantine alchemy finds itself. 1 Surviving Arabic alchemical texts are much more numerous but only marginally better studied. 2 On top of this, historians of Byzantine and Arabic alchemy alike must work with the slippery term "alchemy" itself, which shifts in meaning from metallurgical recipes, Alexandre Roberts is Associate Professor of Classics at the University of Southern California. His research focuses on Byzantine and medieval Middle Eastern intellectual history. He is the author of Reason and Revelation in Byzantine Antioch: The Christian Translation Program of Abdallah ibn al-Fadl (California, 2020). His current work examines theories of chemistry and their repercussions in Byzantine and Middle Eastern culture.