The effect of chronic alcohol consumption on the concentration of 25-hydroxyvitamin D3, total retinol, and retinol-binding protein in serum was studied in chronic alcoholics (n = 12) and controls (n = 19). Ethanol intake during the last year was 178 +/- 116 and 3.7 +/- 4.5 g/day, respectively (p less than 0.002). Of the alcoholics, 58% had a concentration of 25-hydroxyvitamin D3 below lower limit of reference (20 ng/ml). Estimated dietary intake of vitamin D last year was not significantly different for the alcoholics and controls. Concentration of calcium in serum was significantly lower in alcoholics than in controls (p less than 0.05). The serum concentration of retinol and retinol-binding protein was similar in the two groups. These observations may be of relevance for some of the clinical findings related to bone disease among heavy alcohol consumers.