SUMMARYA morphological and biochemical analysis was made of cornified envelopes isolated from patients with different congenital disorders. Nomarski contrast microscopy of the envelopes showed that their morphology was not greatly altered in several types of keratoderma and parapsoriasis, but it was grossly modified in ichthyotic disorders. The various types of ichthyoses, keratoderm ‐lysine isopeptide bonds. In the epidermis two morphologically distinct types of CEs have recently been identified:4a polygonal rigid type (CEr) and an irregularly shaped type with a fragile appearance (CEf) which, in healthy skin, is only present in the lower part of the stratum corneum. These two types possibly represent two successive steps of CE maturation. The stratum corneum of normal subjects contains mainly CEr, whereas the scales in psoriasis contain a much higher proportion of CEf. Keratinocytes in submerged cultures are only able to form CE