Active infective endocarditis is one of the most serious diseases of the heart. Infection often causes periannular abscess, and may also spread to affect the mitral valve structures. This complication carries a high mortality rate and valve replacement followed by intensive care and antibiotic treatment may be the only option to save patients' lives. Severe hemodynamic depression caused by bacterial shock, is today no longer a counter-indication, and the second major risk factor, that of postoperative reinfection, has been greatly reduced by using homografts and new valve prostheses that are resistant to bacterial infection. Timely operation, before complex destruction of cardiac structures occurs, achieves a much higher rate of survival. This assessment of the results of surgical treatment of active infective endocarditis was performed at the German Heart Institute Berlin. It focuses on preoperative investigation and proposes a new classification of this endocarditic disease.