Proteolytic enzymes have been used for wound debridement for many years. The two enzymes most widely used in Europe are fibrinolysin/desoxyribonuclease and collagenase. Despite their frequent use, very few placebo-controlled studies comparing the enzymes with vehiculum only, or with each other, are available. In a specially developed necrotic ulcer animal model, combined with a computer image analysis technique to measure necrotic and total wound surface areas quantitatively, we assessed the wound-cleansing properties of fibrinolysin/DNase oleogel, collagenase ointment, saline-soaked gauze control treatment, and new galenic formulations of collagenase, including placebos. The average relative area of necrotic tissue present in the wound after 1 week was 31% for collagenase ointment and 56% for fibrinolysin/DNAse oleogel (P = 0.0037). Collagenase gel was significantly (P = 0.0007) better in removing necrosis than placebo (gel only). Fibrinolysin/DNAse was not significantly more effective than the three placebo or control treatments (placebo film, placebo gel, saline-soaked gauzes). We conclude that collagenase is a suitable enzyme for wound debridement, but we were not able to detect clinical efficacy of fibrinolysin/DNAse in this model.