The effect of long-term valproate (VPA) treatment on bone mineral density (BMD) in adult epileptic patients is not clearly known, although several studies have been done in children. In adult epileptic patients (it = 50; 24 men, 26 women) treated with VPA, the bone mineral density at lumbar level (L I -L4) and neck, trochanter, and intertrochanter regions of left femur was studied by dual energy X-ray absorptiometry (DXA) at the beginning of the study and after 6 months, with the specific aim to evaluate the effect of long-term valproate monoteraphy on bone mineral density. Routine biochemical parameters were also evaluated. Sixty healthy control subjects were evaluated. Control subjects were similar to patient group with respect to age, race (all White), geographic area, and socioeconomic status.