Epidermal growth factor receptor (EGF-r) expression and tumor cell proliferation rate have been proposed as potential prognostic parameters in renal cell carcinoma (RCC). In this study, immunohistochemical stains using antibodies to EGF-r and the cell proliferation marker Ki-67 (MIB-1) were used to study the relationship between EGF-r expression, tumor cell proliferation, and prognosis in 50 non-papillary RCC extending beyond the renal capsule (pT3). A high Ki-67 labeling index (LI) was associated with poor patient prognosis (P < .05). Thirty-eight cases (76%) expressed strong cell membrane immunoreactivity for EGF-r. There was a tendency toward a shortened survival for EGF-r-positive tumors (P = .08). Tumor growth fraction (Ki-67 LI) was significantly higher in EGF-r-positive tumors than in EGF-r-negative tumors (P < .05), suggesting that rapid tumor proliferation might be responsible for the poor prognosis associated with EGF-r-positive RCC.