Prevalence and factors which may influence the development of osteoporosis have been assessed in 32 chronic alcoholic males by measuring the bone mineral density (BMD) of the lumbar spine and femoral neck by dual photon absorptiometry. Serum bone Gla-protein, as an index of bone formation, 25-hydroxyvitamin D, testosterone and cortisol levels were also measured. Eleven patients (34%) had osteoporosis. In seven the lumbar BMD was below the fracture threshold. Lumbar and femoral neck age-matched BMD were below mean normal values in 20 and in 23 patients, respectively. Moreover, the age-matched BMD was significantly lower in the femoral neck (91.7 +/- 14.4%) than in the lumbar spine (100.1 +/- 17.1%) (P < 0.001). Duration of alcoholism was significantly higher in patients with age-matched BMD below 100% than in those with age-matched BMD above 100%. Bone GLA-protein and 25- hydroxyvitamin D were below normal levels in 67% and 56% of patients, respectively. Serum testosterone was normal in all but two patients, and cortisol was within normal values in all patients tested. In addition a direct correlation was found between the days of abstinence before the study and serum levels of bone GLA-protein (r = 0.64, P < 0.001). In conclusion, chronic alcoholics frequently have bone loss of the lumbar spine and femoral neck related with the duration of alcohol intake. The correlation between bone-GLA protein levels and the days of abstinence suggests that alcohol directly depresses bone formation. Likewise, the low levels of vitamin D also support that this deficiency may contribute to the development of osteopenia in chronic alcoholism.