Hyperthyroidism combined with rhabdomyolysis is extremely rare. There are only 6 reported cases of hyperthyroidism accompanied with rhabdomyolysis in the medical literature. Rhabdomyolysis is a syndrome involving the breakdown of skeletal muscle, and this causes myoglobin and intracellular protein to leak into the circulation. The causes of rhabdomyolysis include trauma, electrolyte abnormality, infection, drug, toxin and hypothyroidism. We report here on a patient who presented with thyrotoxic periodic paralysis and rhabdomyolysis with hypokalemia. He complained of lower leg paralysis along with muscle tenderness, and the laboratory findings showed elevated creatine kinase (CK) levels. After treatment by hydration, potassium replacement and drug medication, including propylthiouracil and beta-blocker, his CK levels were normalized and his symptoms were much improved. For patient with thyrotoxic periodic paralysis and muscle tenderness, the possibility of rhabdomyolysis should be clarified by examining the CK levels.