Intra-abdominal adhesions develop in over 90 per cent of patients undergoing laparotomy. Peritoneal fibrinolysis is believed to be important in the pathophysiology of adhesion formation. This study investigated the fibrinolytic response of postoperative peritoneal fluid in 12 patients undergoing elective laparotomy. There was a significant reduction in the plasminogen activating activity to undetectable levels at 24 h, which was sustained at 48 h (P < 0.05). While there was an early reduction in the concentration of tissue plasminogen activator (median 40.0, 28.2, 16.3 and 31.9 ng/ml at 2, 6, 24 and 48 h respectively; P < 0.05), the abolition of functional fibrinolytic activity appeared to be secondary to a marked increase in the concentration of plasminogen activator inhibitor (PAI) 1 (median 86, 196, 800 and 730 ng/ml at 2, 6, 24 and 48 h respectively; P < 0.05) and PAI-2 (median less than 6, 12, 155 and 245 ng/ml at 2, 6, 24 and 48 h respectively; P < 0.05). This reduction in the plasminogen activating activity of peritoneal fluid may favour the formation of permanent fibrous adhesions following surgery.