Hereditary congenital hypotrichosis is an autosomal dominant pilar dysplasia first described by Marie Unna in an extended German family. The diffuse hair defect typically occurs as an isolated phenomenon and the ultrastructural hair findings consist of both torsion and longitudinal grooving of the hair shaft. A large pedigree comprising 6 generations with 20 members affected by Marie Unna hypotrichosis from Italy is reported.