Small doses of vitamin D can probably prevent catastrophic skeletal demineralization in patients taking antiseizure medication. Moderate doses of vitamin D can reverse this degree of demineralization once it has occurred. Prophylactic vitamin D therapy was associated with a lowered incidence of seizure patients in the overall fracture census and a decrease in the number of in-hospital days for treatment of seizure patients with fractures. Vitamin D therapy should probably be used as a routine dietary supplement in all seizure patients at dosage levels of approximately 400 units daily. Much larger doses (50,000 units once or twice weekly) should be as necessary when these patients sustain fractures or other injuries.