In 1901, Hans Vörner observed a family with a diffuse non-transgredient palmoplantar keratoderma of autosomal dominant inheritance. Histopathologically, he found epidermolytic hyperkeratosis as a characteristic sign and diagnostic criterion of this disorder. We performed a follow-up study of the family originally seen by Vörner in 1901 with clinical, histopathological, and molecular investigations. Clinically, affected family members showed the typical diffuse keratoses over the entire surface of the palms and soles sharply bordered by red margins. A mycotic infection was additionally found in two patients examined. Histopathological investigations confirmed epidermolytic hyperkeratosis. Molecular studies revealed a novel mutation in keratin 9, N160I, in patients from the family. The mutation in the coil-1A domain is thought to have a dominant negative effect on the assembly of keratin intermediate filaments, explaining the dominant inheritance of the phenotype. These findings give further evidence that palmoplantar keratoderma of Vörner represents the same entity as palmoplantar keratoderma of Thost, which was recently re-evaluated in Thost's original family and shown to be caused by a similar mutation, R162 W, in the same segment of keratin 9.