Objectives: evaluate breastfeeding self-efficacy and its associated factors in puerperal women assisted at a public health system in Brazil. Methods: it is a cross-sectional analytical study, with convenience sampling and two instruments: sociodemographic, personal and clinical, and Breastfeeding Self-Efficacy Scale (BSES-SF), applied to puerperal women in a puerperal outpatient clinic at two public maternity hospitals in Goiânia/GO, from September to November 2019. Inclusion criteria: mothers in puerperal period, age above 18 years, children born at term and on exclusive breastfeeding. Exclusion criteria: report depression and premature wean. Results: 128puerperal women were interviewed. The average age was 26.7 (± 5.9) years old. The levels of self-efficacy were high (95.3%) and no puerperal had a low level. The variables with statistical significance were: experience in breastfeeding (p= 0.0312), not having received information on breastfeeding during pregnancy (p=0.0292), did not receive other milk at the maternity (p=0.0380), did not feel pain while breastfeeding (p=0.0242), being able to breastfeed on demand (p=0.0124), presence of breast engorgement (p=0.0207), presenting protruding nipples (p=0.0427). Conclusions: clinical and personal aspects were identified as risk factors for early weaning. This can provide information for the training ofprofessionals and structuring the interventions in health services, with a view in preventing these risks.