Lichenoid tissue reactions or Interface Dermatitis are some of the commonly encountered clinical and histological presentations in dermatology and pathology. The term Lichen refers to a group of skin diseases characterized by eruptive skin lesions which are grouped together as they resemble the algae lichen found growing on rocks. Interface dermatitis can be classified based upon the cell type that dominates the infiltrate or by the intensity of the interface inflammation. This review focusses in detail on lichenoid interface dermatitis and oral lichenoid reactions.