We report a case of severe leptospirosis complicated with a multiple organ failure syndrome. A 62-year-old patient presented a picture associating fever, asthenia and myalgias, particularly intense on the calves. The assessment showed acute renal failure, hyperbilirubinemia, severe rhabdomyolysis and thrombocytopenia. Although initial management associating amoxicilline and continuous veino-venous hemodiafiltration, evolution was unfavourable, with SDRA and increase of hyperbilirubinemia. Administration of a bolus of 500 mg of methylprednisolone, associated with intravenous immunoglobulin (0,4 g/kg per day during five days), led to a rapid clinical and biological improvement. Immunomodulation aspects during leptospirosis are discussed.