The current understanding of xenon scintillation physics is summarized and keyed to the use of xenon as a γ‐ray detector in medical radioisotope imaging systems. Liquid xenon has a short scintillation pulse (∼10−8sec) and high γ‐ray absorption and scintillation efficiencies. The fast pulse may facilitate imagingin vivodistributions of hot positron sources and allow recovery of additional spatial information by time‐of‐flight techniques. We begin by describing our own study of the feasibility of making a practical positron scanning system, and consider the problems of scintillation decay time, linearity, efficiency, purity, and electric‐field amplitifcation. The prospects for a practical instrument are considered.