To identify reasons for the high incidence rates of stomach cancer in Poland, we conducted a population-based case-control study in Warsaw. Cases were residents aged 21 to 79 years who were newly diagnosed with stomach cancer between March 1, 1994, and April 30, 1997. Controls were randomly selected from Warsaw residents registered at the nationwide Polish Electronic System of Residence Evidency, frequency-matched to cases by age and sex. Information on demographic characteristics; consumption of cigarettes, alcohol, tea and coffee; diet; medical history; family history of cancer; occupational history; and living conditions during adolescence was elicited by trained interviewers using a structured questionnaire. Included were 464 cases (90% of eligible) and 480 controls (87% of eligible). Among men, the risk of stomach cancer was significantly elevated among current smokers (OR = 1.7, 95% CI = 1.1-2.7) but not among former smokers. The excess risk was largely confined to long-term and heavy smokers, with significant 2-fold excess risk among men who smoked 40 or more pack-years. Among women, an 80% increase in risk was observed in both current and former smokers but dose-response trends were less consistent than among men. Alcohol consumption was not clearly related to risk, and no association was found for drinking regular coffee or herbal tea or using milk/cream in coffee or tea. A significant reduction in risk was linked to daily tea drinking among women, but not among men. Our findings confirm an association with cigarette smoking, which is estimated to account for approximately 20% of stomach cancers diagnosed among Warsaw residents during the study period.