150 16-40 year old women divided into 3 groups based on dosage and administration intervals were given injections of 6alpha-methyl 17alph a-hydroxyprogesterone acetate for up to 9 months postpartum to study the drugs contraceptive effectiveness for socially handicapped strongly motivated people. Each group received either 50 100 or 400 mg in each 3-month period. Contraceptive efficiency was 100% during the study. Most common side effects were nervousness irritability nausea weight increase and deviation from normal menstrual cycles. The higher the dose the greater was the deviation from normal menstrual cycles. Menstrual anomalies were reversible. Amenorrhea was well tolerated by the patients who were told it might occur. Endometrial biopsies at the end of treatment showed mild symptoms of endometrial atrophy changing spontaneously to a normal proliferative pattern after a time interval. There were no abnormalities in blood count or kidney and liver function.