Abstract: Ki-67 immunostaining was performed on 41 renal cell carcinoma (RCC) sections todetermine its prognostic significance. Ki-67 labeling index of those who developed tumor recurrence was significantly higher than that of recurrence-free cases (P0.001).In the multivariate analysis, Ki-67 labeling index (P=0.005, relative importance:100)was the most important factor affecting recurrence comparing with size(P=0.007,relative importance: 44.74), stage (P=0.018, relative importance: 36.98) and age (P=0.023). The correct rate of Ki-67 index in predicting the recurrence reaches to 90.2%.The results show that the Ki-67 labeling index is a very good,independent,prognosticmarker for RCC.