It is reported on four girls aged 8 to 20 with Incontinentia pigmenti (Ip) The ectodermal dysplasia was associated with oligophrenia, therapy resistant epilepsy with severe psychorganic syndromes and dementia, Lennox syndrome, lability of emotion with severe disorders of social adaptations, spasticity, hypo- and areflexia, hemiathetosis, choreiform unrest, pathological EEG findings, including spike-potentials; relations to cleidocranial dysostosis, dysraphia, Poland's, Greig's and Chotzen's syndrome were found. Ip means unfavourable prognosis and progression of neuropsychiatric disorders.