ABSTRACT:Objective: To identify factors associated with breastfeeding in the first hour of life. Methods: A cross-sectional study conducted among mothers and children under one year of age, who attended the second stage of the polio vaccination campaign in the Federal District, Brazil, in 2011. The sample was composed of 1,027 pairs of mothers and children. Breastfeeding in the first hour of life was considered as the dependent variable; and the independent variables were: socio-demographic characteristics of the mother, prenatal, delivery and postpartum care, reference to physical or verbal violence/neglect during delivery, and children health. Unadjusted and adjusted prevalence ratios (PR) were used as measures of association, calculated by Poisson regression. Results: The prevalence of breastfeeding in the first hour of life was 77.3%. Inadequate prenatal care (PR = 0.72), cesarean section (PR = 0.88) and no access to rooming-in after birth (PR = 0.28) were factors that interfered negatively in breastfeeding in the first hour of life. No factor was associated with breastfeeding in the first hour of life for mother and children. Conclusions: Factors related to health services such as prenatal care, type of delivery and postpartum rooming-in interfered with breastfeeding in the first hour of life, indicating that health services, as well health professional practices were major determinants the breastfeeding in the first hour of life.