Background: Elase is a widely used ointment consisting of a combination of 2 proteolytic enzymes, fibrinolysin and desoxyribonuclease (DNAse). It is said to promote debridement of necrotic and purulent debris from skin ulcers. Objective: Our purpose was to assess the efficacy and safety of this ointment and its components in the treatment of chronic ulcers of the lower extremity. Methods: This was a double-blind, randomized, prospective study of 84 patients with leg ulcers exhibiting necrotic and purulent debris, who were treated for 21 days with twice-daily applications of the ointment, fibrinolysin, DNAse, or who received the ointment vehicle (placebo). We assessed 6 efficacy features: ulcer size, purulent exudate, necrotic tissue, erythema, pain, and overall condition of the lesion at days 8, 15, and 21 after initiation of treatment. We also assessed the frequency of adverse effects. Results: All treatments produced some improvement in the efficacy parameters and overall condition of the ulcers by week 3, but no statistically significant difference was found when compared with placebo. No serious adverse effects were noted. A later retrospective reanalysis of the data found a statistically significant reduction of purulent exudate only at days 3 and 7 of treatment in the group treated with the complete ointment, but not in the other features. Conclusion: The proteolytic ointment provides no long-term clinical benefit in reducing purulent exudate, pain, erythema, necrotic tissue, or overall condition of chronic leg ulcers when compared with either of its two components or placebo. (J Am Acad Dermatol 1998;39:737-40.)