For several years the protease chymotrypsin has been among the available adjunctive treatments for traumatic injuries in which tissue hemorrhage and edema present a problem.1The toxicity of this material has been studied, and it has been found to be relatively nontoxic.2However, being protein in nature it might be expected to elicit a sensitivity reaction in susceptible persons. A survey of the literature revealed a report on only one such sensitivity reaction.3This note constitutes a report of a reaction to aqueous chymotrypsin (Chymar) in which sufficient sensitivity was built up over nine days to produce serious anaphylactic shock. Report of a Case The patient was a 19-year-old man who was admitted to the University Health Center on Oct. 17, 1959, after an acute facial injury sustained in varsity football competition. A diagnosis of multiple fractures of the right maxilla was made. Because of intense edema,