Increased pigmentation of the skin due to melanin occurs in many unrelated conditions and is produced by a variety of causes. It is usually possible to differentiate between types of pigmentation and to classify them as entities resulting from local or systemic causes. Congenital and progressive pigmentation is seldom described. Because of its rarity such a condition associated with dystrophy of the nails and slight atrophy of the skin in two sisters and a cousin is reported. REPORT OF CASES Case1.—K. K., a 29-year-old housewife, the eldest of four children, was born in the United States of Greek parents. Her mother, who died of septicemia at 47 years of age, had normal brunette coloring. Her father, aged 65, has blue eyes and fair skin. A sister, aged 28, has melanoderma, described in Case 2. A second sister, aged 22, has normal brunette coloring, and a brother,