Immunoreactive-somatostatin (ir-SS) concentrations of the gastric mucosa and mood state in patients with functional dyspepsia were examined. The subjects were 12 patients with upper abdominal discomfort, nausea and/or vomiting (motility disorder group) and 14 patients complaining of upper abdominal pain (ulcer-like disorder group) for more than a month without any organic upper-gastrointestinal tract disease proven by endoscopy. These patients were compared with either an age- and sex-matched group of asymptomatic outpatients without any organic disease (control group: n = 26) or to a group of patients with peptic ulcer (n = 19). Somatostatin concentrations of the stomach were measured by radio-immunoassay, and the mood state of each subject was assessed by Manifest Anxiety Scale (MAS) and Self-rating Depression Scale test. Immunoreactive-somatostatin concentrations of the gastric mucosa were significantly higher in the ulcer-like disorder group than in the peptic ulcer, motility disorder or control group, and gastric juice levels were higher in the ulcer-like disorder group. The psychometric tests showed that the motility disorder group was more depressive than the ulcer-like disorder group, but there were no differences between the motility disorder, ulcer-like disorder and peptic ulcer group in MAS scores or environmental factors. These results indicate that there may be two different subgroups in functional dyspepsia influenced by both ir-SS concentration of the stomach and/or mood state.