We performed a study to analyze epidemiological characteristics and bacteriological profile of infectious endocarditis (I.E) in the area of Sfax (Tunisia). We analyzed, retrospectively, all cases of I.E, according to Duke Criteria, hospitalized in the CHU Hédi Chaker of Sfax between January 1997 and December 2000. Bacteriological investigation included blood culture, cardiac valve culture and serology. Seventy-two cases of I.E were diagnosed. The average of age was 32.3 years. 47.3% of the patients did not have cardiac disease, 25% had a valvular prosthesis, 20.8% a native valvulopathy and 6.9% a congenital cardiopathy. Antecedent of acute rheumatic fever was noted in 66% of I.E on native valvulopathy and in 55.5% of I.E on prosthesis. The mitral valve was involved in 39%, the aortic in 27.5% and the two in 26% of the cases. The origin of bacteremia was found or supposed in 55.5% of the cases and was commonly dental (33 % of EI). The bacteriological diagnosis was positive in 51 cases (70.8%). Staphylococci were isolated in 17 cases (23.6%), Streptococci in 17 cases (23.6%) and dominated by oral streptococci (12 cases). Chlamydial serology was positive in 8 cases (11.1%). Diagnosis of infectious endocarditis due to Chlamydia pneumoniae was confirmed in a case by genomic amplification (PCR) and in situ hybridization on the valve. Endocarditis in Tunisia remains frequent. It reaches with predilection the young person in particular with rheumatic heart diseases. The bacteriological profile remains dominated by Streptococci and the Staphylococci.