Tumor-associated proteases play a major role in determining the biologic behavior and aggressiveness of prostate cancer. Several authors have described the association between the increased levels of urokinase plasminogen activator in the plasma and in the malignant prostatic tissue with the metastatic potential of prostate cancer. However, the direct effect of this activity in producing fibronogenolysis in patients with prostate cancer has not been addressed. To evaluate the role of chemotherapy in reversing fibrinogenolysis in patients with prostate cancer, eight patients with hormone-refractory prostate cancer, bleeding, and laboratory evidence of primary hyperfibrinogenolysis were treated with docetaxel. The drug was given 48 hr after initiation of all supportive measures. Laboratory data, including plasminogen, alpha 2-antiplasmin, and fibrinogen, were recorded before and after treatment. Prostate-specific antigen (PSA) was measured at the time of referral and before subsequent cycles (3 weeks). Five patients had resolution of the fibrinolytic process after one cycle of treatment with docetaxel. This was demonstrated by improvement in both the laboratory parameters and the bleeding episodes. Further follow-up showed stabilization of the hematologic parameters and reduction in PSA values in these patients. Two patients died from uncontrolled bleeding despite all supportive measures. One patient did not demonstrate response to this treatment in terms of normalization of the fibrinolytic indicators or reduction in PSA. Primary fibrinogenolysis associated with metastatic prostate cancer is a serious complication. Docetaxel appears to be effective in reversing this process in some hormone-refractory patients. Although this response appears to be due to antitumor activity, a direct effect on the fibrinolytic pathway induced by the tumor cannot be excluded. Further work in this area is warranted.