[Recurrent fever, nocturnal sweating, weight loss].

A 69-year-old woman was admitted to the hospital for fever of unknown origin with nightsweats and weight loss. Diagnosis of endocarditis lenta with streptococcus viridans and a preexisting mitral-valve prolapse with small regurgitation jet was established. Signs and symptoms of endocarditis lenta are stressed in the discussion. Special attention is given to transesophageal echocardiography and to the connection of endocarditis with mitral-valve prolapse.