The incidence of complete hydatidiform mole in Paraguay is 0.23-0.25 cases per 1,000 pregnancies. The incidence is as high at the extremes of reproductive age as at other ages. That finding is at variance with long-accepted concepts. The incidence in the 15- to 19-year age group is lower than earlier, with a greater use of contraceptives in the older group. Complete mole is a rare condition with a high incidence in certain geographical areas.