OBJECTIVE: Gender-specific differences in incidence of renal cell carcinoma (RCC) and its outcome have previously been reported. We used age as a surrogate to test whether this might be hormone-related in a large international RCC cohort. METHODS AND MATERIALS: This study included patients treated by nephrectomy at 10 international academic centers. Clinicopathologic features were assessed using chi-square and the Student t-tests. Kaplan-Meier survival estimates and Cox proportional hazards models addressed the effect of gender and age on disease-specific survival. RESULTS: Of the 5,654 patients, 3,777 (67%) were men and 1,877 (33%) were women. Generally, women presented at lower T stages (P<0.001), had fewer metastases (P<0.001), and had lower-grade tumors (P<0.001). Women more frequently had clear-cell (87% vs. 82%) and less frequently had papillary RCC (7% vs. 12%) than men (P<0.001). Women had a 19% reduced risk of death from RCC than men (hazard ratio 0.81, 95% confidence interval 0.73-0.90, P<0.001). The survival advantage for women was present to the greatest degree in the age group<42 years (P = 0.0136) and in women aged 42 to 58 years (P<0.001), but was not apparent in patients aged 59 years and older (P = 0.248). Age was an independent predictor of disease-specific survival in women (hazard ratio 1.011, 95% confidence interval 1.004-1.019, P = 0.004), but not in men. CONCLUSIONS: As a group, women present with less advanced tumors, leading to a 19% reduced risk of RCC-specific death compared with men. This survival difference is present only in patients aged<59 years. Because this gender-based survival difference is not related to pathologic features, the role of hormonal effects on the development and progression of RCC needs to be investigated.