Abstract Fibrinolytic response was investigated in 71 patients with different malignancies and compared with findings in 30 healthy persons. Euglobulin lysis time, fibrinolytic activity on fibrin plate, tissue plasminogen activator (t-PA) activity and antigen before and after venous occlusion and the fast-acting inhibitor to t-PA (PA-inhibitor) were performed. Fifteen patients (21%) showed low fibrinolytic activity on fibrin plate after venous occlusion (low responders), whereas all control subjects showed a positive response (p < 0.03). t-PA activity was significantly lower in patients (p < 0.003) and t-PA antigen showed no significant differences between patients and controls in post-occlusion samples. PA-inhibitor was significantly higher in patients (p < 0.0002). We conclude that defective fibrinolysis in malignancy, resulting of highly increased PA-inhibitor levels in combination with low t-PA activity, and may have pathogenetic implications.