This study was aimed to evaluate weight variation in 3183 women using the injectable contraceptive Cyclofem. All women were allocated to groups according to their weight at admission. The weight gain was inversely proportional to the weight at admission. The groups of women weighing less than 50 kg at admission, experienced a higher increase 2.8% in four months, and they continued gaining weight, reaching 7.7% in 13 months. Women weighing more than 64 kg at admission did not present any weight change in 4 months and increased only 1.7% at 13 months. When women were classifed as discontinuers due to weight increase, discontinuers due to other reasons, and continuers, at four months, the differences in the mean weight between the groups was statistically significant only in the groups weighing 55 kg or more at admission. At 13 months, the results were similar and the differences were statistically significant only in the groups weighing 55-59 kg and 60-64 kg. Discontinuation rates due to weight increase were proportional to the weight at admission. This rate was almost three times higher in the group of women weighing more than 64 kg at admission than in the group weighing less than 55 kg (p < 0.001). In conclusion, considering the data presented in this study, it is impossible to recommend health providers to inform women who choose Cyclofem as their contraceptive method, that this method may increase their weight throughout its use.