Personality changes have been reported in chronic constipation. Hostility is an important personality factor involved in psychosomatic disorders. The aim of this study was to investigate hostility in patients with chronic constipation. Sixty subjects with chronic constipation (24 males, 36 females, mean age 44.5 years) were investigated with the hostility scale of the Minnesota Multiphasic Inventory. The patients were divided in four groups according to their symptoms: functional chronic constipation (Group I, n = 18), irritable bowel syndrome expressed as chronic constipation and abdominal pain (Group II, n = 21), irritable bowel syndrome expressed as chronic constipation, abdominal pain and bloating (Group III, n = 13) and irritable bowel syndrome expressed as chronic constipation alternating with episodes of diarrhoea (Group IV, n = 8). Twenty-five clinically healthy subjects were investigated as controls. Hostility was as follows (mean +/- SD): 68 +/- 9 in group I, 62 +/- 12 in group II, 70 +/- 14 in group III, 56 +/- 12 in group IV and 40 +/- 12 in controls. The scores were significantly higher in all groups of patients with constipation versus controls (p < 0.01; < 0.001; < 0.001; < 0.02, respectively). These data suggest that hostility is increased in patients with chronic constipation. It is rather a feature of the functional bowel disorders than of constipation, as symptom, only.