PIP: The current incidence of ovulation following therapeutic abortion was established. The return of ovulation following term deliveries in nonnursing mothers has been reported as 13% within 43 days and 30% within 90 days, with the earliest at Day 33. In this investigation, patients were advised to return on the 1st or 2nd day after the 1st menstrual period following the therapeutic abortion. At this time, an endometrial biopsy was done and contraceptive advice given. If the endometrial biopsy indicated that ovulation had occurred, the date of ovulation was considered to have been 14 days before the onset of the current menses. Basic body temperature charts currently prepared by patients were used as adjuncts. All abortions had been done by suction curettage during the first 12 weeks of gestation. Of the 169 patients participating, only 91 were accepted for analysis but in only 72 of them were complete data obtained. Of these, 61 were shown to have ovulated prior to the time of the endometrial biopsy and 11 had not. All but 1 of those ovulating had done so prior to the 36th day after abortion. The mean day was 22 and the earliest verified ovulation was on the 10th postabortal day. The basal body temperature graphs correlated to within 72 hours in 26 of the 61 (43%) ovulating patients. No temperature graphs in the nonovulating patients indicated ovulation. This study indicates that contraceptive advice should consider the possibility of conception taking place in the 2nd week after therapeutic abortion. A commentator at the presentation of this paper stated that secretory endometrium is not certain evidence of ovulation. However, it is concluded that the endometrial evidence of previous ovulation was dependable.