Hypothyroid myopathy has so far been reported in long standing cases of hypothyroidism. We describe two adult patients with myopathy associated with acute transient hypothyroidism. Both presented with severe muscle aches and cramps, stiffness and spasms. Muscle enzymes were markedly elevated and electromyography in one patient showed myopathic features. Histological changes were absent in muscle biopsy, probably because of the short duration of metabolic disturbance. The myopathy subsided promptly when the hypothyroid state was reversed.