A 55-year-old man had rhabdomyolysis and myocardial damage induced by palytoxin. Weakness and myalgia of four extremities occurred five hours after eating a fish. Rhabdomyolysis developed and the serum creatine phosphokinase (CK) was elevated to 40,000 IU/l on the 3rd day. Gastric lavage with activated charcoal and forced mannitol-alkaline diuresis therapy were performed. The patient recovered with no complication such as renal failure. In this case, palytoxin was suggested to induce myocardial damage which was demonstrated by an elevation of the myosin light chain level and a change in electrocardiogram.