25-Hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, calcium, phosphate and parathyreoidal hormone levels were assessed in 34 patients with schizophrenia (DSM-III-R, 44% female, mean age 38.9 +/- 2.1 years), 30 patients with alcohol addiction (16% female, mean age 48.7 +/- 2.2 years), 25 patients with major depression (56% female, mean age 57.6+/- years) and 31 healthy controls. Only 25-hydroxyvitamin D3 and 1,25-dihydroxvitamin D3 levels were significantly lower in all groups of psychiatric patients than in normal controls, but not phosphate, calcium and parathyreoidal hormone levels. Significant differences in the vitamin D levels could not be found between the three psychiatric groups. These findings do not support the idea that vitamin D is specifically involved in the pathophysiology of depression. The difference in patients as compared to the healthy controls might be related to a different social background resulting in differing habits e.g. of nutrition.