Inherited hair and nail diseases have long been considered a group of rare and obscure disorders with a largely unknown genetic basis. In the postgenomic era, a large portion of the genes that are responsible for these genetic disorders has been identified, yielding new insights into the complex molecular pathways that regulate the development and biological function of epidermal appendages. This article reviews the recent progress accomplished in this field and discusses the novel clinical and experimental observations in several hair and nail genodermatoses.