PURPOSE valve prolapse (MVP) cases, complicated with infective endocarditis (IE), seen at a cardiologic reference hospital. METHODS The MVP cases were diagnosed within a series of 276 cases of IE without previous cardiac surgery with clinical-echocardiographic criteria. We emphasised in our study; a) incidence; b) age and sex distribution; c) risk factors for IE; d) clinical-bacteriological data; e) echocardiographic features; f) therapeutic aspects; f) evolution and complications. RESULTS a) We diagnosed 40 (14.4%) cases of MVP; b) mean age of 40.6 years, with 29 men (72.5%); c) dental procedures without prophylactic antibiotic-therapy in seven patients (17.5%), mitral regurgitation in 33 (82.5%), mitral valve redundancy in six (15%); d) fever was found in all patients (100%), cachexia was diagnosed in eight (20%), polyarthritis in six (15%) and congestive heart failure in six (15%). A systolic murmur of mitral regurgitation was found in all the patients and a nonejective click was encountered in four (10%), a Streptococcus was cultivated in 30 (75%), Staphylococcus in three (7.5%) Haemophilus sp in three (7.5%) Peptostreptococcus products in one (2.5%) and negative in three (7.5%) patients; e) echocardiographic signs of vegetation in 23 (57.5%), mitral regurgitation in 33 (82.5%), rupture of mitral chordae in 11 (27.5%) and mitral redundance in six (15.2%); f) 37 (92.5%) patients were medically treated and three (7.5%) required surgery; g) we registered in the hospital evolution: stroke in 10 (25%) and noncerebral mycotic aneurysm in 2 (5%) cases, two patients died (5%), one due to a hemorrhagic complication after surgery of bioprosthesis implantation and another of rupture of a cerebral mycotic aneurysm. CONCLUSIONS The MVP was frequent in the population of patients with IE with of patients with mitral regurgitation, and male with mean age greater than the other cases. We observed low incidence of surgical need (7.5%) and lethal outcome (5%) but frequent (25%) neurological complications.