Focal dermal hypoplasia is a rare genodermatosis characterized by developmental defects of the skin, resulting in widespread linear lesions of dermal hypoplasia with adipose tissue in the dermis. We describe a 13-year-old girl who has typical cutaneous lesions which have been present since birth; she also has some of the associated dental, nail and skeletal abnormalities, while an X-ray of the long bones osteopathia striata is visible, a feature seen in a high proportion of cases of focal dermal hypoplasia. Eighty-eight per cent of the case reports in the literature are of females and X-linked dominance is the likely mode of inheritance. It has also been proposed that the condition is lethal in homozygous males and the high frequency of miscarriages on the maternal side of this patient's family is consistent with that lethality in males. The literature, particularly with regard to pathogenesis and inheritance, is discussed.