1. An enhanced collagenolytic activity in the bowel tissue samples of M. Crohn and ulcerative colitis is demonstrated. 2. No inhibition of the collagenolytic activity was found when the specific collagenase inhibitor EDTA was applied. 2. In vitro, the application of EGLIN B resulted in a significant decrease of collagenolysis. EGLIN is a recently detected inhibitor of serine proteases such as Elastase.