Leukonychia totalis is described in a mother and leukonychia partialis in her two daughters. This is the first report of hereditary leukonychia of two different types in one family. A survey of reported cases of hereditary, congenital, and acquired leukonychia is included. There are four major types of leukonychia: Total, partial, striate, and punctate. All but the punctate type may be congential or hereditary. Inheritance appears to be of the autosomal dominant type. All four forms may be acquired. Total and partial leukonychia usually follow a severe, long-standing systemic disorder or local insult. Leukonychia striata may follow either a relatively short or recurrent systemic disorder or local trauma. Leukonychia punctata is a very common phenomenon and appears to result from periodic minor local trauma to the nail matrix. Pathogenesis of leukonychia is not established with certainty. Opacity of the nail plate due to abnormal keratinization probably is the primary defect.