Background. Peritoneal fibrinolytic capacity decreases during abdominal operation. This may be a local effect or a part of a generalized response to the procedure. Methods. Plasma and paired peritoneal biopsy specimens were taken at Intervals during abdominal operation, and fibrinolytic components were assayed in plasma and tissue extracts. Values are given as medial [interquartile range]. Results, In peritoneal tissue there was a gradual decrease of tissue-type plasminogen activator (tPA) activity and at 90 minutes of the operation differed significantly from that of the initial sample (1.0 [1.0] ng/mg protein, and 5.1 [6.5] ng/mg protein, respectively, p < 0.05). The tPA activity levels at the wound were significantly lower (1.0 [1.0] ng/mg protein) at 90 minutes compared with a remote peritoneal site (1.8 [1.9] ng/mg protein, p < 0.05). At the wound the tPA activity correlated significantly with time (r = -0.48, n = 26, p < 0.01). tPA activity and antigen peaked in plasma at 30 minutes (p < 0.05) and 60 minutes (p < 0.05), respectively. Plasminogen activator inhibitor type 1 activity increased in plasma during operation (p < 0.05), but was not detectable in peritoneal samples. Conclusions. The intraoperative changes in tissue tPA activity were not consistently reflected in plasma samples. These findings suggest that the reduction in peritoneal fibrinolysis during abdominal operation is a local response to trauma.