Oral lichen planus (OLP) is a chronic mucosal condition commonly encountered in clinical dental practice. Lichen planus is believed to represent an abnormal immune response in which epithelial cells are recognized as foreign, secondary to changes in the antigenicity of the cell surface. It has various oral manifestations, the reticular form being the most common. The erosive and atrophic forms of OLP are less common, yet are most likely to cause symptoms. Topical corticosteroids constitute the mainstay of treatment for symptomatic lesions of OLP. Recalcitrant lesions can be treated with systemic steroids or other systemic medications. However, there is only weak evidence that these treatments are superior to placebo. Given reports of a slightly greater risk of squamous cell carcinoma developing in areas of erosive OLP, it is important for clinicians to maintain a high index of suspicion for all intraoral lichenoid lesions. Periodic follow-up of all patients with OLP is recommended.