Purpose: The purpose of this study is to clarify the relevance of breastfeeding and its preventive effect on maternal hypertension as well as to evaluate the theoretical mechanism behind of it through systematic evaluation of existing articles. Methods: For systematic evaluation of literatures in recent 5 years, 5 most suitable articles were selected with the key words, (breastfeeding or breastfeed or lactation) AND (hypertension or high blood pressure or hypertensive disorders) from PubMed, EMBASE, and Cochran Library, and carefully reviewed by 2 researchers. Results: Breastfeeding women have less frequently developed hypertension in their later life. Depending on the duration of breastfeeding, compared to nonbreastfeeding women, breastfeeding women’s odds ratio for developing hypertension are 0.87 (95% confidence interval [CI], 0.76-0.99), 0.83 (95% CI, 0.68-1.00), and 0.79 (95% CI, 0.65-0.97) each for 0-6 months, 6-12 months, and greater than 12 months of breastfeeding. As the number of breastfeeding children increases, the incidence of maternal hypertension decreases. In addition, both partial and exclusive breastfeeding lower the risk of developing maternal hypertension. Though the mechanism of prophylactic effect of breastfeeding on hypertension is not conclusive, reset hypothesis, oxytocin release, the increase of ghrelin and protein peptide YY, as well as epigenetic programming are considered to be relevant to the etiology of the condition. Conclusion: Breastfeeding prevents maternal hypertension later in life. Studies show dose-response relationship of breastfeeding as the duration matters. In addition, both partial and exclusive breastfeeding have preventive effect on maternal hypertension. Numerous mechanisms are continuously being reported and further studies are needed for clarification.