This chapter provides detail description of Lichen planus and other lichenoid disorders. Chapter has 2 well illustrated diagrams and pictures. Infectious diseases, Lichen planus, commonly implicated drugs in lichenoid reaction, clinical features of lichen planus, hair and nail involvement in lichen planus, lichen striatus, lichen nitidus, lichen spinulosus, Gianotti-Crosti syndrome, lichen sclerosus, pityriasis lichenoides, keratosis lichenoides chronica, frictional lichenoid eruption and graft versus host disease are described in detail. 2 tables are included to highlight commonly implicated drugs in lichenoid reaction and conditions associated with Gianotti-Crosti syndrome. 42 references are included at the end of the chapter to facilitate further reading.