In 1952 Ito described the occurrence of a bilateral systematized depigmented nevus in a 22-year-old Japanese woman. He used the term incontinentia pigmenti achromians. The condition has been described under various designations, such as for instance Ito's hypomelanosis. Till now 71 patients with this syndrome are described. We will report 4 cases, 2 boys and 2 girls, 2 Caucasian, 1 Indonesian and 1 Caribean child. The cutaneous signs in these 4 patients fit in with the syndrome of Ito's hypomelanosis. Of these 4 children 3 are mentally retarded, 2 have epilepsy. Congenital malformations are seen in 3 children. Electronmicroscopy of skin biopsies of the hypomelanotic nevus and of the normal skin were performed. In the biopsy of the normal skin of one patient interruption of the basement membrane is seen. Anomalies of the central nervous system as seen in our patients occur in about 40% of the cases. Abnormalities of skin derivatives next to other ectodermal anomalies are described. Affection of other germ layers also occur to a varying degree. In our 4 patients some of these abnormalities exist also. These 4 cases are presented to underline the fact that this syndrome seems not to be as extremely rare as is proposed.