To evaluate the association between the level of implementation of the Brazilian Breastfeeding Network and the prevalence of exclusive breastfeeding.Cross-sectional study of a representative sample of 916 infants < 6 months, in Ribeirao Preto, SP, Southeastern Brazil, in 2011. Data on breastfeeding, place of outpatient care and other characteristics were collected during the National Vaccination Campaign. The factor studied is where outpatient care took place: Private; Non-Network Public; Public with Network Workshop; and Public certified by Network. The individualized effect of the factor studied on the outcome was analyzed using Poisson regression with robust variance.The comparison between private (reference category) and other outpatient care showed significant dose-response relationship with a progressive increase in the prevalence of exclusive breastfeeding in public non-Network, public with Network Workshop and public accredited by Network outpatient care (p = 0.047). As regards the Basic Health Units accredited by Network category, the Prevalence Ratio of exclusive breastfeeding was equal to 1.47 (95%CI 1.00;2.17), after adjustment for confounding variables.The prevalence of exclusive breastfeeding for infants < 6 months was higher in places accredited by the Brazilian Breastfeeding Network, which evinces the importance of investing in accreditation of Basic Units of Health by this strategy.