Correlation: breastfeeding mothers who are employees, educated above primary school, or were medical staff-guided had the higher proportion of right knowledge; mothers who are employees, educated above primary school, or the distance from birth of 2 years or more had the higher proportion of right attitude; mothers who are in suburban, or have two children or more are in practice better. Conclusions: According to breastfeeding mothers with infants under 6 months old to visit department of the Children Hospital 1, Ho Chi Minh City, Viet Nam from Jan 12, 2009 to April 30, 2010, the majority of them had the right attitude, knowledge but the proportion of mothers with the right practice was low.