Six hundred and eight women were treated with 200 microgram of ethinylestradiol and 2 mg of dl-norgestrel, administered in two divided doses, as a postcoital contraceptive. Criteria for entry into the study included definite unprotected coital exposure within the previous 72 hours and the absence of any contraindications to the use of estrogen/progestin-containing compounds. Women with coital exposures outside of the 72-hours-to-treatment time frame were excluded. Four hundred and sixty-four of the patients were cycling regularly and, of these, 152 were exposed at midcycle. Only one patient became pregnant as a result of probable method failure as compared with the minimal estimated number of 12 to 30 pregnancies.