A survey among users and health personnel participating in the Salvadorian Social Security Institute (ISSS) Family Planning Program revealed interest in including a monthly preparation for injection as a contraceptive method offered by this Institution. The formulation containing dihydroxyprogesterone acetophenide (DHPA) 150 mg + estradiol enantate (E2EN) 10 mg was chosen for conducting an open and prospective study of efficacy and tolerability. Between January 1992 and March 1994, 7054 women were treated with this product for a total of 60010 months. A sample composed of 4505 women treated at this Institution confirmed that average users are young, have one or two children, do not show a particular geographical distribution and choose the monthly injection instead of oral contraceptives as the first contraceptive method or for the puerperium. The study formulation showed a high efficacy (Pearl Index: 0.018) and tolerability (general withdrawal rate throughout the study: 27.09%). The most frequent adverse events included bleeding disorders, headache and mastalgia; their incidence decreased spontaneously from the sixth month (3.9%), reaching 0% after two years. Treatment was discontinued due to adverse events in 3.47% of women. No significant bodyweight or systolic and diastolic blood pressure alterations were observed. Based on these results, the monthly injectable contraceptive was included in the basic product list at ISSS.