Lichen planus is a chronic immunological disorder affecting skin and mucous membranes, being the oral cavity one of the more affected areas even as a first or only manifestation of the disease. Its etiology is unclear, but it has been associated with the activation of autoimmune mechanisms. Oral lichen planus (OLP) has a wide spectrum of clinical manifestations including a variety of white lesions, red lesions or a combination of both. In addition, its histopathological features are not always specific. Because of the above, the diagnosis of OLP can be challenging, especially for clinicians who are not entirely familiarized with the disease. OLP treatment is aimed in reducing pain and discomfort, usually with topical steroids. If treatment with topical steroids is unsuccessful, second line treatments include calcineurin inhibitors and systemic steroids. Care has to be taken when using these drugs as they can have considerable adverse side effects. OLP is classified by the WHO as a potentially malignant disorder with a malignant transformation rate estimated between 1.5% and 5%. Thus, its correct diagnosis and proper follow-up are essential even in asymptomatic forms of the disease. This to detect early clinical changes indicative of malignant transformation to an oral squamous cell carcinoma (OSCC).