Periodic paralysis is a rare neuromuscularion channel disorder manifested by transient painless muscle weakness. It is classified as hypokalemic, hyperkalemic or normokalemic depending on blood potassium levels. Thyrotoxic periodic paralysis is a very rare form of hypokalemic periodic paralysis, affecting 0.1% to 2% of all patients with hyperthyreosis. It is much more common in males than in females. Altough a very rare condition, one must always look for anomalities in thyroid function tests when encountering a patient with acute muscle weakness and hypokalemia since the management of thyrotoxic periodic paralysis differs from the management of familial hypokalemic paralysis. Treatment consists of potassium replacement and propranolol and once euthyroidism is restored the attacks of TPP no longer occur.