The hematologic and obstetric problems of nine pregnant patients with acute leukemia are analyzed. Seven patients received chemotherapy during various trimesters of pregnancy, four during the first 10 weeks, and there was no evidence of congenital malformations in any of their offspring. Six of nine babies are alive and healthy with a normal growth 2 months to 15 years after birth, one child was stillborn, and two children died 21 and 90 days after birth. These results were compared with others in the literature and the conclusions are that pregnancy is not a contraindication for treatment of acute leukemia, that cytotoxic drugs may not cause congenital malformations, and that the management of pregnant patients with acute leukemia should be carefully planned.