Lichen planus is the most common dermatologic disease with oral manifestations, and oral lichen planus (OLP) is one of the more common mucosal conditions a clinician is likely to encounter in his or her practice. It is an immunologically based, chronic, inflammatory, mucocutaneous disorder of undetermined etiology. While research over the past decade has dramatically improved the overall understanding of the underlying pathogenesis of OLP, specific details of its pathogenesis and a clear understanding of why certain patients are afflicted while others are not, remains elusive. The care and management of patients with OLP continues to challenge even the most experienced clinician, and strongly suspected associations with chronic liver disease and oral squamous cell carcinoma further complicate matters. To provide prudent and competent care, oral health care providers must have a basic understanding of the impact the disease and/or its treatment may have on their patients.