Thyrotoxic periodic paralysis; is a rare sign of thyrotoxicosis and characterised by attacks of muscle weakness. Hypokalemia is usually present during attacks. A 33-year-old male patient admitted to emergency service of our hospital with complaints of generalised muscle weakness which was more prominent in his lower extremities. Thyrotoxicosis and hypokalemia were detected in his examination. Hypokalemia signs were present in electrocardiography; intravenous potassium replacement had been started immediately. After potassium replacement; his complaints rapidly recovered. Thyrotoxic signs in Thyrotoxic periodic paralysis can be overlooked because neurological signs are more prominent during attacks. Early diagnosis in these patients prevents severe cardiopulmonary complications.

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