We describe a case of a 39-year-old male, who initially presented with severe muscle pain, fever, shortness of breath and tachycardia. He was admitted to hospital with suspected myocarditis. The next days he developed a generalized icterus and acute renal failure. Suspecting leptospirosis an intravenous therapy with penicillin was started. Due to pulmonary and circulatory insufficiency intensive care was necessary. In course the patient developed all known manifestations of leptospirosis including, cardiac arrhythmia and asystolia due to AV-block III degrees, recurrent atelectases of the lungs, hyperbilirubinemia, thrombocytopenia, hepatitis, pancreatitis, very severe rhabdomyolysis and polyradiculitis with areflexia and tetraplegia. Additionally, the patient had a transient hyperthyreosis, which has not been described in the literature so far. After 33 days the patient left the intensive care unit and was discharged out of hospital a fortnight later. 4 weeks later he was able to return to work. The only residuum of this illness is a partial paresis of his right quadriceps muscle.