A subgroup of patients with nonulcer dyspepsia (NUD) have no definite cause for their dyspepsia, termed essential dyspepsia. The aim of the present study was to determine if environmental factors are associated with essential dyspepsia. The patterns of ingestion of analgesic drugs (aspirin, acetaminophen, dextropropoxyphene), nonaspirin, nonsteroidal antiinflammatory drugs, alcohol, coffee, tea, and smoking in 113 essential dyspepsia patients were compared with 113 randomly selected community controls matched for age, sex, and social grade. Associations were studied in two six-month periods, before diagnosis in all patients and before the onset of NUD in those patients with a short history of dyspepsia. It was found that acetaminophen ingestion was associated with essential dyspepsia, and this association was present both before the onset of the dyspepsia (OR 3.1, 95% CI 1.3- 7.1) and before diagnosis (OR 1.8, 95% CI 1.2- 2.6). None of the other environmental factors were associated with essential dyspepsia.