Disorders of keratinization can be very severe and disfiguring diseases causing considerable handicap to the patients. This chapter provides a detailed discussion on icthyosis, both inherited and acquired icthyosis along with the icthyosiform syndromes with relevant photographs. This is followed by a brief note on the less common entities like Darier’s disease, porokeratosis, palmoplantar keratoderma and acanthosis nigricans. The important features of palmplantar keratoderma are summarized in a tabular form.