A 9-year-old mentally retarded girl had a systematized leukoderma in the configuration of whorls and streaks that began during the first year of life. No other family members were affected. Histologic examination of a hypopigmented area revealed decreased amount and patchy distribution of melanin in the basal layer of the epidermis. There was no loss of pigment into the underlying dermis. The clinical and histologic features of this case correspond to those previously reported in the Japanese and European literature as incontinentia pigmenti achromians (Ito). Although certain clinical features of this rare syndrome are similar to those found in incontinentia pigmenti (Bloch-Sulzberger), the relationship between the two remains unproved. At present it seems best to consider incontinentia pigmenti achromians as a variant of hypochromic nevus even as Ito did in describing the original case.