Urokinase-type plasminogen activator (uPA) and the uPA receptor (uPAR) are involved in a proteolytic cascade resulting of extracellular matrix degradation. Upstream, uPA and uPAR are regulated by various factors including hepatocyte growth factor (HGF), which stimulates the uPA/uPAR proteolytic system and increases invasion of cancers. We recently demonstrated that HGF induces invasion of DU145 prostate cancer cells into collagen gel matrix. We therefore examined effects of HGF on uPA and uPAR expression in DU145 cells. Effects of HGF on uPA expression in culture medium were determined by Western blotting and fibrin zymography, effects on uPAR expression in cell-associated protein were examined by Western blotting. HGF increased uPA and uPAR production in a dose-dependent manner up to 10 ng/mL, while effects of 20 ng/mL were approximately equal to those of 10 ng/mL. HGF stimulated uPA production beyond that in control cultures from 8 h until 48 h after HGF addition. HGF stimulated a uPA/uPAR proteolytic network in DU145 cells, which may be important for acquisition invasive potential by prostate cancer.