OBJECTIVES To analyze the incidence of multifocality in renal carcinoma. METHODS A retrospective study was conducted to determine the incidence of multifocality in renal carcinoma. We analyzed 50 surgical specimens from patients with renal carcinoma who had undergone radical nephrectomy at our institution between September, 1992 and December, 1994. RESULTS 9 of the 50 specimens (18%) had more than one lesion in the same kidney. CONCLUSIONS The incidence of multifocality in renal carcinoma has been reported to range from 6% to 30%, which implies that if conservative surgery is performed, the likelihood of tumor recurrence is not negligible. We believe therefore that radical surgery must be performed, except in those cases where conservative surgery is mandatory (solitary kidney, bilateral tumors).