A 71-year-old male undergoing hemodialysis for chronic renal failure presented with proximal muscle weakness. He had normal levels of serum creatine phosphokinase. The results of nerve conduction velocity studies and a needle-exploration electromyogram were normal. Ultrasonography revealed adenomatous enlargement of the parathyroid glands, and he had marked elevation of the serum parathormone level. The level of serum free carnitine before hemodialysis was significantly lower than normal, while the acyl/free ratio was high. However, the muscle carnitine content was within the normal range. Interestingly, partial inactivation of carnitine palmitoyltransferase activity in the muscle was observed in association with the elevation of the serum parathormone level. Uremic myopathy in this case may be caused not only by abnormal carnitine metabolism but could also be attributable to the partial carnitine palmitoyltransferase deficiency associated with secondary hyperparathyroidism.