The aim of this study was to assess the current practice of antibiotic prophylaxis of Bacterial Endocarditis (BE) among General Dental Practitioners (GDPs) in Spain. GDPs were asked over the telephone by a fictitious patient what antibiotic prophylaxis they would administer to an "at risk" patient for BE before a tooth extraction. Four hundred randomly selected Spanish GDPs were surveyed, 200 of them were asked about BE prophylaxis in penicillin non-allergic patients and the remaining 200 in penicillin allergic patients. Of the GDPs surveyed, 182 (45.5%) did not recommend any prophylactic treatment; 74.7% of those stated that an oral examination before treatment was needed and 25.3% referred the patient to his/her physician or cardiologist for further advice. Of the 97 GDPs who recommended antibiotics to penicillin nonallergic patients, only 30 (30.9%) suggested the prophylactic guidelines proposed by the American Heart Association or the British Society for Antimicrobial Chemotherapy. For penicillin allergic patients, 68.2% of the GDPs prescribed erythromycin as the antibiotic of first choice, while 17.6% of the GDPs prescribed clindamycin. Nonetheless, fewer than 30% administered both antibiotics with the adequate dosages. These results show important gaps in the knowledge of antibiotic prophylaxis for "at risk" patients before dental procedures among Spanish GDPs.