This review evaluated the knowledge of health professionals (HP) about breastfeeding and factors that leading the weaning. A search was performed in four electronics databases and the grey literature. The search strategy included Mesh terms and synonyms. No language or date restrictions were adopted. Studies that evaluated the knowledge of HP about breastfeeding and weaning were considered eligible. The studies retrieved by the searches were evaluated by two independently examiners. From 1,417 studies retrieved, 35 were included. Many countries and professionals from different health areas were analyzed. No studies evaluated the dentists' knowledge. Although the included HP know the benefits of breastfeeding for health, the length of breastfeeding recommended by the World Health Organization, exclusive or not, was not aligned with all professionals' endorsement. Information about weaning is scarce; however, HP are mindful of the main potential causes of early weaning. The knowledge of HP is conflicting about breastfeeding and unusual about weaning. Furthermore, no studies were found that presented data on the knowledge of dentists on the subject. Thus, assessments of dentists' knowledge and education measures for HP are necessary since they are frequently questioned about these issues.