A thirty year old woman in whom an uncommon complication of smallpox vaccination developed is presented herein. In this case, virus was transmitted from the recently vaccinated child to the vulva and the vagina of the incompletely immune mother. The diagnosis was confirmed by a viral culture and a direct smear. The patient was treated intravenously with cytosine arabinoside (Cytosar) 3 mg/kg and was completely cured after seven days.