Deo-medroxyprogesterone acetate (DMPA) 150 mg every 3 months, was administered as a contraceptive to 752 patients who were studied for 44 months. Side effects were similar to those seen with oral contraceptive agents. The major unwanted symptom was a completely unpredictable bleeding pattern. Regularity of bleeding cycles can be enhanced by monthly administration of enthinyl estradiol for 7 days. Only one drug-failure pregnancy occurred; fifty-four pregnancies occurred before, during, or after DMPA. No deleterious effects on pregnancy could be noted. Seventy-five percent of the patients conceived within 12 months after discontinuing DMPA. One patient developed questionable thrombophlebitis, but no cases of thromboembolic phenomenon were seen. DMPA appears to be a highly effective contraceptive agent, well-suited to a clinic-type population requiring infrequent motivation.