Many red and white lesions of the mouth are clinically indistinguishable from those of oral lichen planus (OLP). These lesions, often referred to as oral lichenoid lesions (OLL), can occur as a result of contact sensitivity (lichenoid contact reactions), drug reactions or as part of chronic graft versus host disease (GVHD). Oral lesions in discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE) can also have a similar clinical appearance to OLP. Distinguishing oral lichen planus from oral lichenoid lesions, lupus lesions, or other red and white lesions of the mouth can be difficult (even impossible) but it is important, for optimal management of each condition. All patients with red and white pathological lesions should be referred to an oral medicine or a local oral or maxillofacial surgery department, where a biopsy and other investigations can help to establish a diagnosis, and appropriate treatment and monitoring can be commenced. Dentists and other members of the dental team, such as hygienists and dental therapists, should also equip themselves with the knowledge to be able to explain different pathologies of the mouth to their patients and discuss risk factors.