Data from a case-control study conducted in New York State during 1982-1984 were used to evaluate the relation between alcohol consumption and estrogen receptor-positive and estrogen receptor-negative breast cancers and alcohol and various histologic subtypes. The cases were women between 20 and 79 years of age with a diagnosis of primary breast cancer. A total of 794 estrogen receptor-positive and 358 estrogen receptor-negative breast cancer cases were available for study. Controls (n = 1,617) were selected from driver's license files of the New York State Department of Motor Vehicles. Information on estrogen receptor status and histology was obtained from hospital records. The risk of estrogen receptor-positive breast cancer was shown to increase with increasing amounts of alcohol consumption in grams per day (odds ratio (OR) = 1.18 (95% confidence interval (CI) 0.88-1.57) for < 1.5 g/day, 1.28 (95% CI 0.91-1.80) for 1.5-4.9 g/day, 1.28 (95% CI 0.96-1.70) for 5.0-14.9 g/day, and 1.35 (95% CI 0.99-1.85) for > or = 15.0 g/day). There was no relation between alcohol consumption and estrogen receptor-negative tumors (OR = 0.92 (95% CI 0.62-1.36) for < 1.5 g/day, 1.19 (95% CI 0.77-1.83) for 1.5-4.9 g/day, 0.94 (95% CI 0.64-1.35) for 5.0-14.9 g/day, and 1.05 (95% CI 0.70-1.59) for > or = 15.0 g/day). The risk for each of the histologic subtypes studied increased with increasing daily alcohol consumption. These findings suggest that alcohol may only increase a woman's risk of estrogen receptor-positive breast cancers.