Abstract Objective: To investigate whether breastfeeding in early life affects blood pressure of preschoolers. Methods: Cross-sectional study nested in a cohort from a municipality in the state of Minas Gerais, Brazil. All children in the cohort were invited for this study. Thus, between 2009 and 2010, blood pressure of 230 preschool children and their mothers, in addition to anthropometric variables, previous history, and socioeconomic status were evaluated. Blood pressure measurement was assessed in the morning, using automatic Omron® HEM-714INT and HEM-781INT devices to measure the blood pressure of preschool children and their mothers, respectively. Logistic regression was used to study the association between breastfeeding and blood pressure. The significance level was set at 5%. Results: This study identified 19 (8.26%) preschool children with high blood pressure (values above the 90th percentile). High systolic blood pressure was associated with low birth weight (OR = 5.41; 95% CI = 1.45-20.23) and total breastfeeding duration of less than six months (OR = 4.14; 95% CI = 1.40-11.95). High diastolic blood pressure was not associated with any variable, whereas high systolic blood pressure/diastolic blood pressure ratio was associated with breastfeeding duration of less than six months (OR = 3.48; 95% CI = 1.34-9.1). Conclusion: The results of this study indicate that preschoolers breastfed for a period of less than six months were more likely to have high blood pressure when compared to those breastfed for a longer period, suggesting a protective effect of breastfeeding against high blood pressure in this population.