To study the effects of meat intake, including heterocyclic amine exposure, on the risk of breast cancer, we conducted a hospital-based case-control study involving 352 patients with breast cancer and 382 controls. A strong effect of red meat, total meat, beef, fried meat, and heterocyclic amine exposure was found, after controlling for potential confounders. The odds ratio for the highest quartile of 2-amino-3-methylimidazo [4,5-f]quinoline exposure was 3.34 (95% confidence interval 1.85-6.02). According to these results, meat intake and chemicals formed during the cooking process appear to be strong risk factors in human breast carcinogenesis.