BACKGROUND. Several investigators have revealed that urokinase-type plasminogen activator (uPA) and its receptor (uPAR) are overexpressed in serum as well as in tumor tissues in patients with various types of cancer. In this study, we examined whether the serum levels of uPA and uPAR could be used as predictors of the progression and prognosis of prostate cancer. METHODS. Serum levels of uPA and uPAR in 54 healthy controls, 62 patients with benign prostatic hypertrophy (BPH), and 72 patients with prostate cancer were measured by a sandwich enzyme immunoassay. RESULTS. The mean serum levels of uPA and uPAR in patients with prostate cancer were significantly higher than those in healthy controls and patients with BPH. Furthermore, the serum uPA and uPAR levels in prostate cancer patients with metastasis were significantly elevated compared with those in patients without metastasis. Among patients who underwent radical prostatectomy, the serum levels of uPA and uPAR in patients with pathologically organ-confined disease were significantly lower than in those with advanced disease. The overall survival rate of prostate cancer patients with elevated serum levels of either uPA or uPAR, or of both, was significantly lower than that of patients with normal serum levels of uPA and uPAR. CONCLUSIONS. The results of this study indicate that the elevation of serum levels of either uPA or uPAR, or of both, could be used as new predictors of progression and prognosis in patients with prostate cancer.