SummaryPlasminogen activators were determined in intestinal tissue, obtained after surgery from patients with Crohn’s disease and ulcerative colitis, and compared with normal intestinal tissue from colorectal cancer patients.The activity and quantity of tissue-plasminogen activator (t-PA) was found to decrease with the severity of inflammation in the patients with inflammatory bowel disease. Urokinase (u-PA) activity, however, was not changed compared with controls or in relation with severity of inflammation. In contrast, the level of u-PA antigen was found to be increased significantly in the inflammatory bowel disease tissues and was also related with severity of inflammation. The difference between u-PA activity and antigen in inflammatory bowel disease tissue could be attributed to an increase in inactive pro-u-PA and u-PA-inhibitor complexes.This increase in u-PA and the concomitant decrease in t-PA, are similar to those found in premalignant colonic adenomas, and might be related to the known increased cancer risk in inflammatory bowel disease.