Ichthyosiform erythroderma is a rare phenomenon occurring in about 1/300,000 live births. Congenital unilateral ichthyosis, described in this case report, is a clinical variant of ichthyosis. Only five previous cases have been reported. In the patient described in this report, superimposed infection of the affected skin developed. Her immunologic system was intact. She manifested failure to thrive, in spite of an adequate caloric intake, and markedly delayed psychomotor development. This patient also demonstrated absorption from the affected dermis of topically applied urea hydrophilic base ointment. She died before her first birthday.