We have studied the effect of different doses of 1 alpha-hydroxycalciferol (1 alpha [OH]D3) on bone mineral density (BMD) of 165 male hemodialysis patients (ages from 24 to 71 years) using dual X-ray absorptiometry (DXA) in a one-year follow-up study. There were no fractures in their lumbar spine participated in the study. 1 alpha (OH)D3 was administered orally at a low dose (0.25 microgram/day, n = 56, Group L) or at a higher dose (0.5 to 1.0 microgram/day, average 0.58 +/- 0.02 microgram/day, n = 65, Group H), and the absolute BMD values and the percent annual changes of BMD were compared with those who took no 1 alpha (OH)D3 (n = 44, Group N). BMD was measured three ways at the start and the end of the study; 1) lumbar spine BMD at anterior-posterior view (AP-BMD), 2) lumbar spine BMD at lateral view (Lat-BMD), and 3) 1/3 distal radius BMD. Plain spinal radiographs indicated no bone fracture before nor during the study. Although there were no detectable changes in the absolute values of BMD during the one-year period, significant differences were observed in the percent annual changes of lumbar spine BMD among the three groups. The annual changes of lumbar spine BMD among the three groups. The annual changes of AP-BMD were -0.4 +/- 0.7%, +0.1 +/- 0.6%, and +2.4 +/- 0.8% in Group N, Group L and Group H, respectively. These changes were statistically significant (p = 0.011 by one-way ANOVA). The positive effect of 1 alpha (OH)D3 on Lat-BMD was also significant (p = 0.028 by one-way ANOVA), while the treatment did not affect the change of BMD at 1/3 distal radius. There was no significant difference among the three groups in the initial or final levels of biochemical parameters including serum calcium, phosphorus, alkaline phosphatase, osteocalcin and parathyroid hormone. These results indicate, in male hemodialysis patients, that oral 1 alpha (OH)D3 treatment is effective in the prevention of lumbar spine BMD loss which is frequently observed in hemodialysis patients.