PIP: A clinical trial of the oral indigenous contraceptive Maswin was conducted on 48 fertile women (ages 26-42) for 1 year covering 538 menstrual cycles. 1 tablet (400 mg Embelia ribes extract) was taken each morning for 10 days beginning on the fifth day of menstration; total dosage was 10 tablets for 1 menstrual cycle. No pregnancies, side-effects, or toxic symptoms occurred. All expressed a sense of well-being and were eager to continue useage of Maswin. Embelia ribes antagonizes the effects of estrogen on the uterus so the uterus is not in the necessary condition to accept fertilized ovum, so pregnancy does not take place even though ovulation and fertilization have occurred.