The effects of the valproic acid and carbamazepine monotherapies on bone mineral density were evaluated. Bone mineral density was measured in 53 children with primary epilepsy taking either valproic acid (n = 25) or carbamazepine (n = 28) for longer than 1 year and in a healthy control group (n = 26) by the dual-energy x-ray absorptiometry method at L2-L4 levels of lumbar vertebrae. The mean serum levels of valproic acid and carbamazepine were 66 +/- 2.2 microg/mL and 7.0 +/- 9.3 microg/mL, respectively, and the mean duration of treatment for each drug was 2.4 +/- 0.2 years and 2.6 +/- 0.5 years, respectively. Calcium intakes in diet were similar in both the control and study groups. The serum levels of calcium and phosphorus in all groups were normal. Bone mineral density values of both valproic acid and carbamazepine groups were not statistically different from that of the control group (P > 0.05).