Lamellar ichthyosis (nonbullous congenital ichthyosis) has been explained as an autosomal recessive trait. We have found an autosomal dominant type of this disorder. Four patients, belonging to three consecutive generations of a family, were affected from birth. The disorder was characterized by large, dark brown scales covering the entire body including flexural folds, palms and soles. X-linked recessive ichthyosis was excluded by clinical appearance, pattern of transmission and normal electrophoretic mobility of beta-lipoproteins. Autosomal dominant ichthyosis vulgaris and bullous ichthyosiform erythroderma were excluded by the histological and ultrastructural features. In the absence of a positive family history, this skin disorder would have been taken for autosomal recessive lamellar ichthyosis. This new autosomal dominant type of ichthyosis should be considered for differential diagnosis, when genetic counselling is given in a sporadic case of lamellar ichthyosis.