A 37-year-old woman with typical features of pseudohypoparathyroidism (chronic tetany, paresthesia, persistent hypocalcemia, round face, short stature, short metacarpals and metatarsals, cucutaneous calcification and lack of response to exogenous and endogenous parathyroid hormone as regards urinary phosphate and cyclic AMP excretion) was treated with oral administration of 2μg/day of 1αOH-vitamin D3. Serum calcium started to rise within 3 days returning to the normal level with disappearance of symptoms referrable to hypocalcemia. Such a favorable effect of a small dose of 1αOH-vitamin D3 in a patient with typical hypoparathyroidism suggests an important role of disturbance of 1 a-hydroxylation of vitamin D3 by the kidney in the pathogenesis of calcium and phosphorus abnormality in this disease. Fortyfour cases of pseudohypoparathyroidism in the Japanese literature were briefly reviewed.