Proteolytic enzyme therapy has been employed in various diseases in which its anti-inflammatory and fibrinolytic effects have been of value. Among such agents, aqueous chymotrypsin (Chymar) has been described as relatively free of undesirable side-effects. In the brochure 1 accompanying this product it is stated that, "Although sensitivity to chymotrypsin is uncommon, the usual precautions should be exercised in those patients with known allergies or sensitivities." The toxicology of both crystalline trypsin and chymotrypsin has been studied by Hendley and associates 2 in extensive animal experiments. Large doses of chymotrypsin administered intravenously resulted in marked lowering of blood pressure and irreversible shock with respiratory arrest and cardiac standstill. Vascular collapse was not a uniform phenomenon but was dependent on species sensitivity. Generalized hemorrhagic diathesis involving lungs, myocardium, intestine, kidneys, and liver was also produced. Chymotrypsin in large doses was found to be a potent anticoagulant. Death in some of these