THE USE of pure, crystalline trypsin in the enzymatic débridement of fibrinopurulent empyema was reported in October, 1950, by Reiser, Roettig and Curtis.1 From this investigation it became evident that its use in treating other necrotic and purulent lesions might offer a marked improvement in or addition to present therapeutic measures. Accordingly, the scope of the investigation was enlarged to try the efficacy of trypsin in a variety of suppurative and sloughing lesions. This is a preliminary report of the results obtained. The enzymatic digestion of necrotic tissue has a historical background of many years, but its practical application has been given little attention. John Hunter was the first surgeon to demonstrate the digestion of dead tissue by animal proteolytic enzymes. Since Hunter's time numerous proteolytic enzymes of both plant and animal origin have been discovered. However, there has been little or no work done to apply these in