Statement of Problem: Congenital heart disease is the most common disposing factor to bacterial endocarditis. Since the people with cardiac disease are in high risk of caries and some microorganisms of endocarditis are due to streptococci (caries initiation), good dental and oral health in these people are very important.Purpose: The purpose of this study was to determine the parent’s knowledge about antibiotic prophylaxis before dental procedure and dental health (dmft/DMFT) of the children at risk of endocarditis. Materials and Methods: This is a cross-sectional descriptive analytical study performed on 84 people subjects (38 M, 46 F) being 2-17 years old and at risk of endocarditis in Amirkola and Shahid Beheshti Hospital in Babol. After clinical examination of the patients and completing of the questionnaires, findings were analyzed according to SPSS program and Chi-Square test.Results: The percentage of parents who understood the meaning of ‘heart infection’ was 42.9% those, who knew the possibility of endocarditis occurrence to be caused by a dental procedure was 57.1%, those who understood the requirement for antibiotic cover before dental treatment was 16.7%, and those who understood the importance of a good oral health to prevent infective endocarditis was 60.7%.Regarding oral health behaviour, 51.2% of children brushed their teeth at least once a day and 48.8% did not brush their teeth or brushed irregularly. Only 2.4% of children referred a dentist every six months and 44% had never visited a dentist before. 26.1% of subjects were free of caries and the mean of dmft was 1.86±2.47 and for DMFT was 2.23±2.97.Conclusion: The parents’ knowledge about the importance of dental health and its role in prevention of endocarditis was low. Absence of caries in these children was low making them susceptible to bacterial endocarditis.Key words: DMFT, dmft, Infective Endocarditis, CHD