Idiopathic hyperphosphatasia is a rare disorder of uncertain cause. Affected children have painful swelling of the limbs and delayed physical development. The roentgenologic changes are characterized by generalized diaphysial expansion and osteoporosis with active subperiosteal new bone formation. Similar involvement of the calvaria is an important feature of the disease. A marked elevation of the alkaline phosphatase level and high levels of acid phosphatase and leucine aminopeptidase are found. To our knowledge, this is the first report of this entity in a child from India.