The authors report the case of a 49-year-old female with a history of rheumatic valvular heart disease who underwent valve surgery in 1997, with implantation of St. Jude prosthetic valves in aortic and mitral position. She was asymptomatic until the end of July 2001, when she was admitted to Garcia de Orta Hospital emergency unit because of heart failure, fever and suspicion of endocarditis. Cardiologic evaluation was requested and the transthoracic (TTE) and transesophageal (TEE) echocardiograms revealed vegetations on the prosthetic mitral valve. Blood cultures were negative. She started empiric antibiotic therapy and the clinical course stabilized in the first week. After ten days of medical therapy her symptoms became worse and TTE and TEE were repeated. TTE showed significant left ventricular-aortic gradient, suggesting aortic valve obstruction. Decreased left ventricular function was now present with hypokinesia in the anterior descending coronary artery territory. In the TEE, a large thrombotic process on the mitral prosthesis valve was seen, with a prosthesis disk blocked. There were similar findings in the aortic valve. Cardiac fluoroscopic images were obtained at the mitral and aortic position confirming the TEE report. The coronary angiogram was normal. Promptly transferred to a cardiac surgery center, the patient underwent aortic and mitral prosthetic valve replacement. The intraoperative findings were compatible with those from echocardiography and cardiac fluoroscopy.