The incidence of preeclamptic toxemia (PET) was investigated in 72 anovulatory, oligomenorrheic and previously nulliparous women who conceived after an induction of ovulation. One-thousand consecutive spontaneous pregnancies and 1,000 pregnancies of primiparae were used as control groups. The anovulatory group consisted of 33 consecutive well-documented cases of polycystic ovarian disease (PCO) and 39 anovulatory patients in whom PCO was excluded (A-NPCO). The results indicate that pregnancies after induction of ovulation are accompanied with a higher incidence of PET. The rate of this disorder was significantly higher in PCO groups than in A-NPCO women (28.5 vs. 4%), when calculated per number of all pregnancies. The difference between the incidence of PET in PCO, A-NPCO, control primiparae and normal control patients was even more pronounced when calculated on the basis of the number of patients (54.5, 12.5, 11 and 2.5%, respectively). Overproduction of steroid hormones, especially androgens, was suggested as the main factor for the appearance of PET in PCO patients.