Four patients with acquired ichthyosis are described and the results of histological, histometric, autoradiographic and enzyme histochemical studies reported. Three of the patients were found to have in addition the following underlying diseases--malnutrition, reticulum cell sarcoma and panhypopituitarism. The fourth patient did not have any systemic disorder and the provoking cause of his ichthyotic condition remains obscure. Clinically these patients demonstrated the skin changes of autosomal dominant ichthyosis although their condition tended to fluctuate in severity. The various studies performed indicated that the histological and metabolic changes tended to reflect the clinical state of the patients and that these parameters did not differ significantly from those observed in atuosomal dominant ichthyosis.