A 61-year-old woman developed rhabdomyolysis and acute renal failure after strenuous walking. She had been treated for seven years with levothyroxine (T4) for hypothyroidism. On admission, her thyroid function test revealed marked hypothyroidism, suggesting poor drug compliance. Electromyographic and muscle biopsy findings were compatible with hypothyroid myopathy. Other diseases that could cause rhabdomyolysis were excluded. Her renal function completely recovered with peritoneal dialysis, and thyroid function normalized with 100 micrograms/day of T4. The present case suggests that rhabdomyolysis could occur in patients with hypothyroidism, especially those with poor drug compliance, in combination with other aggravating factors such as exercise.