The aim of this case control study was to define the strength of the associations of smoking, alcohol, and heavy analgesic ingestion with chronic gastric ulcer (GU). Ninety-nine patients were interviewed about smoking, alcohol, and analgesic ingestion for the 6 months before exacerbation of their chronic GU. The 180 non-ulcer community control subjects were frequency-matched with the patients for the characteristics of age, sex, and social status. Smoking, alcohol, and heavy analgesic ingestion were studied when present as sole factors and in combinations. Their associations with GU were measured by the odds ratio (OR) and the adjusted odds ratio (AOR). Smoking in male patients (OR 15.4) and heavy analgesic ingestion in female patients (OR 23.4) were significant as sole factors. Smoking plus heavy analgesic ingestion was significant in female patients (OR 10.0), and the combination of all three factors was significant in male patients (OR 13.0) and in female patients (OR 6.3). Smoking had significantly increased AORs of 3.3 in male patients and 3.5 in female patients; alcohol had a significantly decreased AOR of 0.4 in female patients; and heavy analgesic ingestion was significantly increased in female patients (AOR 7.2). It is concluded that smoking in all patients and heavy analgesic ingestion in female patients are risk factors for chronic GU. Alcohol, however, does not appear to be a risk factor.