Aim: To analyse the effect on body weight of continuous hormonal contraception by releasing subdermal implant etonogestrel (ENG) in women of reproductive age treated in the family planning consultation of a Venezuelan hospital. Methods: Comparative and applied research, with quasiexperimental, case-control, open label and prospective design, with an intentional sample of 60 women separated to receive the contraceptive implant (Implanon NXT (R); cases) or a cooper intrauterine device (IUD) (Cooper T; controls) was carried out. Body weight and body mass index were evaluated before and after 12 months of contraceptive use; as well as demographic characteristics of users, side effects, and contraceptive effectiveness of each method. Results: After one year with the ENG implant, no significant variations were found with respect to initial measurements of body weight (61.21 +/- 8.30 vs. 61.23 +/- 9.50, p>0.5) and BMI (25.23 +/- 3.89 vs 25.26 +/- 4.30; p>0.05); on the contrary, to what was observed among IUD users where both body weight and BMI had a significant increase (P<0.0 5). Likewise, most users remained in the same weight range as when starting the method (p<0.001); while weight gain was greater among IUD users (1,530 +/- 2.04 vs. 3,700 +/- 3.02; p<0.05). Conclusions: The ENG implant does not produce an increase in body weight after 12 months of use, with minimal adverse effects and high contraceptive efficacy.