Breast engorgement is a common problem of mothers in the postpartum period. If this problem is not detected and treated properly, it can affect the lactation and lead to breast abscess. Early perception and having knowledge about breast engorgement will help mothers preventing breast problems. This study assessed knowledge and explored factors related to breast engorgement of mothers. The cross - section design was used in this study. Data were collected from 245 postpartum mothers at Obstetric Department in Thai Nguyen National Hospital. Participants were interviewed through available questionnaires.

          The findings of the study revealed that 79.2% of mothers who had knowledge and 20.8% of mothers who had no knowledge about breast engorgement. There was no correlation between age, occupation, income, residence and knowledge about breast engorgement of mothers (p –value > 0.05). There was a correlation between the level of education, the number of mothers' births and knowledge about breast engorgement of mothers. Significant differences were (p –value < 0.05).