Objective: To assess the influences of the knowledge of parents about hepatitis B virus (HBV) infection and the benefit of HBV vaccination on the practice of HBV vaccination among children. Methods: A prospective cross-sectional study recruited parents whose children, aged 12-24 months, received HBV vaccination at Commune Health Centers (CHCs) in Ho Chi Minh City from Feb. 2016 to Jul. 2017. Parents were interviewed using a questionnaire that included 11-item binary knowledge questions and checked their children's vaccination cards. Results: A total of 768 parents had a mean age of (30.8±5.1) years. The mean knowledge score of the 11- item questions was (7.0±2.4). The knowledge score was positively associated with full and timely HBV vaccination. In addition, children who received complete and timely HBV vaccination were significantly more likely to live in rural areas (Adjusted OR 4.02, 95％ CI 2.79-5.79, P<0.001). Also, children whose parents received vaccination information from health care providers, and had knowledge about HBV risk, had a higher rate of full and timely HBV vaccination (Adjusted OR 1.60, 95％ CI 1.13-2.29, and Adjusted OR 1.47, 95％ CI 1.01-2.13, P all<0.05). Conclusions: Parents possessed a great deal of incorrect knowledge about HBV. More health education from health care providers should target parents living in specific locations and focus on the benefits of HBV vaccine.