Thyrotoxic periodic paralysis (TPP) is a disorder that affects a small percentage of patients with hyperthyroidism; the patients are predominantly Asian men. Two typical cases are presented here; both patients came to the emergency room with complaints of sudden onset of weakness. Their symptoms were initially resolved through treatment for acute hypokalemia. Additional tests identified the patients as being thyrotoxic for which condition they underwent thyroid ablation with radioiodine. No further episodes were reported for either patient. Often the underlying cause of the weakness or paralysis is undetected because of the absence of clinical symptoms of hyperthyroidism and because clinicians are unfamiliar with the disorder. It is imperative that TPP be recognized in the differential diagnosis of weakness and that the underlying thyrotoxicity is treated to permanently alleviate the condition. The authors discuss the epidemiology, etiology, clinical manifestations, and treatments of TPP.