Background: Hypokalemia is commonly encountered during paralysis in patients with thyrotoxic periodic paralysis (TPP) and may contribute to neuromuscular manifestations. This condition mainly affects male patients of Asian descent. With increasing population mobility and admixture, TPP as the presenting feature of hyperthyroidism is more common in Western countries and Gulf area. TPP is an alarming and potentially lethal complication of hyperthyroidism characterized by muscle paralysis and hypokalemia due to a massive intracellular shift of potassium. A potassium supplement has been recommended to hasten recovery and prevent cardiopulmonary complications. However, this recommendation has not yet proven efficacious. Hyperadrenergic activity has been implicated in the pathogenesis of TPP. We tested whether nonselective β-blockers could terminate neuromuscular symptoms rapidly while reducing an intracellular shift of potassium. Methods: We describe 7 patients who had an acute attack of TPP with characteristic hypokalemia. Results: After oral propranolol, 3 mg/kg, serum potassium concentrations increased promptly in all patients, and there was complete amelioration of paralysis. Only 3 patient needed short term K supplement for their sever hypokalemia and sever symptoms. No rebound hyperkalemia was detected. Conclusion: Given propranolol efficacy in this study, propranolol should be considered as a first-line therapy for TPP.