ABSTRACT Objective: to analyze the changes in prevalence, median duration and correlates of breastfeeding in a small city in São Paulo state, Brazil. Method: analysis of two cross-sectional studies, conducted at intervals of one decade, with 261 and 302 children younger than two years, respectively. We used Kaplan-Meier survival analysis for calculation of the median duration of breastfeeding, and Cox regression for correlates analysis, with significance level of 5%. Results: an increase of 33.4% in the prevalence of exclusive breastfeeding and 20.9% in breastfeeding was identified. Regarding the latter, the median duration increased from 7.2 to 12 months. In the most recent study, the median duration was lower in first-born children who used pacifiers, and it was not associated with breastfeeding incentive actions. Conclusions: advances in the prevalence and duration of breastfeeding were observed during the 10 year-period, however, pacifier use still remains associated to a shorter median duration of breastfeeding. Our findings contribute to highlighting the need for intensification of nursing actions in the promotion of breastfeeding, and discouragement regarding the use of pacifiers.