Thyrotoxic periodic paralysis is an acute muscle weakness of the limbs associated with hypokalemia. It can occur with any form of thyrotoxicosis. Thyrotoxic periodic paralysis associated with transient thyrotoxicosis due to thyroiditis is very rare. We experienced a case of thyrotoxic periodic paralysis associated with transient thyrotoxicosis. A 39-yr-old man was referred to our hospital because of paralysis of upper and lower extremity. The laboratory results were hypokalemia and mild thyrotoxicosis. A thyroid scan with Tc-99m revealed decreased uptake in the thyroid area compatible with destructive thyroiditis. The paralytic attack did not recur after the patient recovered to euthyroid state.