Two patients suffering from ichthyosis with unusual ultrastructural features were examined. One was a 14-year-old boy with ichthyotic skin since birth. The ichthyosis was initially erythrodermic and later presented as follicular hyperkeratosis. The other patient was an ichthyotic child who died 2 days after birth of respiratory distress syndrome. Although apparently not consanguineous, both families came from the same relatively isolated rural area and autosomal recessive inheritance seems likely. Light microscopy did not yield diagnostic features, but the ultrastructural findings in the granular and horny cells showed diagnostic lamellar membrane packages. Identical ultrastructural features have previously been published in one prematurely born baby who died soon after birth and once in a prenatal diagnosis in the same family; the disease was termed "ichthyosis congenita type IV".