In a controlled prospective study performed in 16 pregnant epileptics and nine normal pregnant controls, biochemical indices of calcium homeostasis (serum calcium, serum magnesium, serum phosphate, and serum alkaline phosphatases) were determined after 18 weeks pregnancy, at birth, 8 days and 6 months after birth. Furthermore, the same indices were measured in their newborns in the first 6 months of life. In both groups of mothers the serum alkaline phosphatase rose significantly during the pregnancy (P less than 0.001), followed by a significant fall after the births (epileptics: P less than 0.05, controls: P less than 0.001), but the epileptic mothers had significantly higher initial serum alkaline phosphatase levels than the controls (P less than 0.05). In both groups of newborns a dramatical fall in serum calcium was observed in the first day of life (P less than 0.001), followed by a normalization after 1 month. The serum alkaline phosphatases doubled between day 8 and day 30 in both groups (P less than 0.001). In the standing debate whether epileptics should be treated prophylactically with vitamin D, the present study indicates that pregnancy in epileptics does not call for extra vitamin D supply, and their newborns do not develop more severe hypocalcemia than their controls.