Cardiovascular involvement by Leptospira is infrequent. However the statistics are under estimated. This paper reports a case of a 39 years old male, who works as a Marine and had traveled to a tropical endemic area for Leptospira in Peru. He was initially admitted with fever, headache and myalgias. He was diagnosed of Leptospirosis (Ig M positive and MAT positive) and malaria and receive specific treatment for both diseases (Doxycycline, Cloroquine, Primaquine). Ten days later he was readmitted with severe leptospirosis when he presented mild chest pain with no pulmonary symptoms. Echocardiography showed pericardial fluid (aprox 300 cc) with no tamponade physiology and pericardial thickening. EKG showed supraventricular arrhythmia (with normal previous EKG) and CPK -M, myoglobin and troponin -I were elevated. There are several reports of cardiovascular involvement in severe leptospirosis but most patients are asymptomatic. Just two cases in 1996 were described, after 20 years we describe a similar case worldwide, and the first time in Peruvian studies. In conclusion we can say that it is very important to follow all patients with uncomplicated leptospirosis and evaluate for cardiac involvement at least with a baseline EKG and cardiac enzymes, to have a comparative study in case they decompensate.