Sub acute left-sided bacterial endocarditis is a serious condition that may be overlooked due to highly variable clinical manifestations. We present the case of a 45-year-old man who presented with complaints of fullness in his abdomen and splenomegaly that referred to the surgery clinic. He underwent diagnostic splenectomy. 3 month after splenectomy endocarditis was diagnosed. We recommend echocardiography in the work up of isolated splenomegaly.