A case of hypokalemic familial periodic paralysis is presented and the litures are reviewed. A 15-year-old boy was admitted to Ewha Womans University Hospital with chief complaints of paralysis of both extremities and trunk on awaking in the morning. He had a history of quadriplegia, 8 months ago. Laboratory study revealed a hypokalemia(1.6mEq/L) and biopsy specimen taken from the gastrocnemius muscle showed mild vacuolization. After treatment with potassium chloride, paralysis was completely recovered.