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Thyrotoxic periodic paralysis (PP) is the most common acquired form of PP in Asian populations, and its cardinaland biochemical abnormality is hypokalemia. We describe a 39-year-old man who had acute bilateral limb motorweakness and paresthesia, and showed normokalemia during attack. Thyroid studies showed subclinical thyrotoxic Goiter.Control of the hyperthyroidism nearly eliminated his PP. Regardless of normokalemia, our patient might be a case ofhypokalemic PP because of improvement from anti-thyroid medication.