Purpose: We determined the incidence of and factors associated with the development of renal cell carcinoma (RCC) in the contralateral kidney after nephrectomy for localized RCC. Materials and Methods: Between 1970 and 2000, 2,352 patients with sporadic, localized unilateral RCC and a normal contralateral kidney underwent nephrectomy for RCC. Cancer specific survival rates were estimated using the Kaplan-Meier method. Univariate Cox proportional hazards models were used to determine associations with outcome. Results: Of the 2,352 patients studied 28 (1.2%) had RCC in the contralateral kidney. including 20 with clear cell and 8 with papillary RCC. Mean time from primary surgery to contralateral recurrence was 5.2 years (median 4.8, range 0 to 18) for clear cell RCC compared with 5.6 years (median 1.3, range 0 to 21) for papillary cell RCC. Positive surgical margins (risk ratio 14.23. p = 0.010) and multifocality (risk ratio 5.74, p = 0.019) were significantly associated with contralateral recurrence following nephrectomy for clear cell RCC, while nuclear grade (risk ratio for grades 3/4 vs 1/2, 4.78, p = 0.040) was significantly associated with contralateral recurrence following nephrectomy for papillary RCC. In patients with clear cell RCC estimated cancer specific Survival rates 1, 3, and 5 years following contralateral recurrence were 93.8%. 80.2% and 72.9%. respectively. Conclusions: In patients with localized RCC and a normal contralateral kidney who underwent nephrectomy for RCC positive surgical margins and multifocality were significant predictors of contralateral recurrence for clear cell RCC, while nuclear grade was a significant predictor of contralateral recurrence for papillary RCC.