Forty-four patients with ectopic pregnancies were followed with serial serum progesterone determinations for up to 40 days after surgery. Seven patients (16%) failed to show luteal function during the study. Thirty-seven (84%) demonstrated luteal activity (serum progesterone at least 3 ng/mL): in six patients by days 17–19, in 50% by day 24, and in 72% by day 30. Because hormonal contraception delayed until the first postoperative office visit would miss the onset of folliculogenesis in approximately three-quarters of ectopic pregnancies, contraception should be begun immediately after surgery.