One hundred patients with functional dyspepsia, 100 patients with duodenal ulcer and 100 healthy controls were assessed on anamnestic factors, somatic symptoms and psychological measures. Patients with functional dyspepsia had significantly higher levels of state-trait anxiety, general psychopathology, depression, a lower general level of functioning and more somatic complaints from different organ systems, especially the musculo-skeletal system, compared to patients with duodenal ulcer and healthy controls. Patients with functional dyspepsia had more frequent dyspepsia symptoms and a longer disease history than duodenal ulcer patients. Discriminant analyses using a model of fifteen psychological and anamnestic variables, classified correctly 71.5% of the subjects due to diagnoses. The test for multiple somatic complaints (Giessener Beschwerdebogen) was the most important discriminating factor (Eigenvalue 0.78). Seventy-five per cent of the patients were correctly classified, 71% by diagnosis with respect to diagnoses of duodenal ulcer and functional dyspepsia using frequency of dyspeptic symptoms as discriminating factor (Eigenvalue 0.40). Functional dyspepsia seems to be a disease entity of its own, distinct from duodenal ulcer and strongly associated with psychological factors.