BACKGROUND: Small asymptomatic solid renal masses are being found more often through the frequent use of abdominal ultrasonography and computed tomography. Nephron-sparing renal surgery is being done more often to treat these small lesions. A retrospective review was done to determine the effectiveness of this treatment. METHODS: Patients who had nephron-sparing renal surgery (group 1-35 patients) were compared with those who had radical nephrectomy (group 2-71 patients) for renal cell carcinoma smaller than 5 cm. RESULTS: The two groups had only small differences in fall in hematocrit, transfusion rates, operative time, and hospital stay. Major surgical complications were more frequent in group 1. After a median follow-up of 3.1 years, there has been no recurrence of tumor and there were no surgery-related or cancer-related deaths in either group. CONCLUSION: Nephron-sparing renal surgery appears to be a safe and effective alternative to radical nephrectomy for localized small renal tumors.