Thyrotoxic hypokalemic periodic paralysis is a rare complication of thyrotoxicosis. This clinic condition is often encountered in Asian populations and male gender while thyrotoxicosis is frequently seen in women. The escape of potassium into cell is the mechanism responsible for this disease and its etiology is not completely known. Thyroid hormones, carbohydrate rich diet, alcohol consumption and excessive exercise are regarded as the precipitating factors. This clinical picture is generally difficult to define at first attack. Here, we report a forty-two-year-old male patient with BasedowGraves disease who was diagnosed as having thyrotoxic hypokalemic periodic paralysis during the first paralytic attack. His symptoms improved after potassium replacement and treatment with beta-blocker and antithyroid drugs. The permanent cure was achieved with radioactive iodine ablation therapy.