In the present study, urokinase-type plasminogen activator (uPA) expression in 150 potentially curatively resected SCCs of the esophagus was analyzed immunohistochemically by means of a murine monoclonal antibody (American Diagnostica, Greenwich, CT) and correlated with survival. Altogether, 122 of the 150 tumors (81.3%) expressed different levels of uPA. Among the 122 uPA-positive tumors, 104 (85.2%) showed a weak staining intensity, and 18 (14.8%) showed a strong staining intensity. Among the uPA-positive tumors, 29 (23. 8%) tumors showed a uPA immunoreactivity in 6-25% of all tumor cells, 30 (24.6%) showed a uPA immunoreactivity in 26-50% of all tumor cells, 41 (33.6%) showed a uPA immunoreactivity in 51-75% of all tumor cells, and 22 (18.0%) showed a uPA immunoreactivity in 76-100% of all tumor cells. No significant correlation could be shown between the different patterns of uPA expression and various clinicopathological parameters, such as pT category, pN category, tumor size, histological grade, blood vessel invasion, lymphatic vessel invasion, and inflammatory response. Concerning the overall postoperative survival, no significant differences between uPA-positive and uPA-negative tumors could be verified. This also held true when different cut points in the percentage of uPA-positive tumor cells were used. In contrast, the intensity of uPA staining provided significant prognostic information in that patients with strongly uPA-positive tumors had a poorer outcome than patients with weakly uPA-positive or uPA-negative tumors. Moreover, as shown by stepwise multivariate Cox regression analysis, the intensity of uPA expression was an independent prognostic factor.