Leptospirosis, an infectious disease that affects humans and animals, is considered the most common zoonosis in the world. The infection causes a systemic illness that often leads to renal and hepatic dysfunction. Eighteen year old woman admitted to our clinic with cough, sore throat, fever, fatigue, maculopapular rash and monoarthritis. Joundice, hepatosplenomegaly and ascites were noted on physical examination. Pericardial and pleural effusion in addition to ascites were seen on computed tomography. Weil's syndrome was diagnosed with direct microscopy and ELISA test of the blood sample. Despite the prompt initiation of penicillin-G treatment with daily 24 million units in six equal doses, the patient died in 48 hours. Six weeks later blood culture result was reported as Leptospira icterohaemorrhagiae. Polyserositis is a rare clinical finding in leptospirosis. Together with fever, joundice, organomegaly and arthritis, Weil syndrome must be included in the differential diagnosis of polyserositis.