This multicentric study was done in order to know the contraceptive efficacy and side effects of subdermal implants liberating levonorgestrel, in Mexican women. Results analysis, at one year, of 246 women, at four medical centers of Mexican Institute of Social Security (IMSS), showed that this contraceptive is highly efficacious, as there were no pregnancies in 2326 months of observation. The main side effects were: menstrual disorders in 34.8% of women; soreness in implantation site in 3.6%; headache in 13.4% and nausea, dizziness and vomiting in 11.6%. The most frequent causes for implant retirement were menstrual cycle alterations, and soreness at implantation site, with 7.3 and 3.5 respectively. The continuity rate at one year was 84.3, which was higher to what has been seen at the Institution with other temporal contraceptive methods, so the implants may be considered as one more alternative in family planning methods.