Previous literature, although not consistent, suggests that moderate alcohol consumption might be associated with decreased risk of renal cell carcinoma (RCC) in women. Thus, we examined the association between alcohol intake and the incidence of RCC by analyzing data from the Swedish Mammography Cohort, a population-based prospective cohort of 59,237 women, aged 40-76 years, who, at baseline in 1987-1990, were cancer free and had completed a food-frequency questionnaire including questions about alcohol consumption. Through June 30, 2004, 132 incident cases of RCC were diagnosed. We used the Cox proportional hazards model to estimate age and body mass index (BMI) adjusted rate ratios (RRs) and their 95% confidence intervals (CIs). Women who consumed >4.3 grams per day of alcohol (ethanol) had nonsignificantly lower risk of RCC than did women who consumed <2.5 g/d (RR = 0.71, 95% CI 0.42-1.19); among women > or = 55 years of age at entry into the cohort, corresponding risk estimates were RR = 0.33, 95% CI 0.10-1.05, p for trend = 0.04 and among women with BMI >25 kg/m2, RR = 0.30, 95% CI 0.09-0.97, p for trend = 0.04. Consistent with these findings, women who drank 1 or more servings of total alcoholic beverages per week had lower RCC risk than did women who drank less (RR = 0.62, 95% CI 0.41-0.94); the corresponding estimate for women > or = 55 years of age was RR = 0.44, 95% CI 0.22-0.88. Results from our prospective cohort study of middle-aged and elderly women indicate that moderate alcohol consumption may be associated with decreased risk of RCC.