Statement of Problem: Dental procedures leading to oral tissue injuries may provoke bacterial release to the blood stream causing infective endocarditis (IE) in vulnerable patients. The guideline which was proposed by AHA has been updated 9 times having the last update published in 2007. This study was endeavored to uncover the level of knowledge of general dental practitioners in Shiraz, concerning the 2007 AHA guidelines for endocarditis prophylaxis in patients with cardiac problems receiving dental treatments.Materials and Method: This cross- sectional and descriptive analytical study included 150 dentists as participants. All practitioners were given a self –report questionnaire which consisted of three sections. Questions were designed to assess their knowledge of antibiotic prophylaxis in patients with cardiac disease. Results: Almost all participants (93%) were aware of antibiotic prophylaxis to be essential for tooth extraction. Most participants did not believe in prophylaxis for noninvasive procedures (such as shedding of primary teeth, impression, intraoral radiography). From all of the respondents, 75% considered Amoxicillin to be the antibiotic of choice and 57% were acquainted with the correct dose of Amoxicillin for high risk patients.Conclusion: The study identified a potential for under/over prescription of antibiotic prophylaxis under the current guideline. Burden of IE necessitates more accurate knowledge of antibiotic prophylaxis in the undergraduate curriculum and continuing education programs of dentistry.