Thyrotoxic periodic paralysis is a rare complication of thyroid – related disorders with hyperthyreosis. It is manifested as a recurrent episodes of hypokalemia and muscle weakness lasting from hours to days. The incidence is highest among Asians, sporadicaly it has been described in other ethnic groups. A case of thyrotoxic periodic paralysis occuring in a man of Vietnam nationality is described, as well as differences of familiar paralysis.

        Key words: thyrotoxic periodic paralysis, hypokalemia, hyperthyreosis, periodic muscle paralysis