Background: Oral lichen planus (OLP) is a relatively common chronic inflammatory oral mucosal disease of unknown cause. Oral lesions in OLP are chronic, rarely undergo spontaneous remission, are potentially premalignant and are often a source of morbidity. Objective: The purpose of our investigation was to describe the clinical characteristics of 35 patients with biopsy-proven OLP. Methods: We reviewed the medical records and clinical photographs of 35 patients who had been diagnosed with OLP during the last 5 years, from January 2001 to March 2006. We identified average age of onset, gender distribution, presence of family history, clinical types, location of the oral lesion, symptoms, associated dermatologic and systemic disease and treatment modalities. Results: Of the 35 patients, 65.7% were women and 34.3% men. The average age of onset for men was 41.2 years and for women was 52.4 years (overall average age of onset was 48.5 years). Only 5 patients had a family history of OLP, which had not been proven by histologic examination. Of the 35 OLP patients, the reticular type was found in 45.7%, the erythematous type in 31.4% and erosive type in 22.9% of patients. The most common site of oral lesions was the buccal mucosa, which was found in 57.1 % of the patients. The lips were the second most commonly involved site at 48.6%, then the tongue at 8.6% and gingiva at 5.7%. Except for the 4 asymptomatic patients, the rest of the patients complained of various symptoms such as a pain, a burning sensation, pruritus and irritation. Many cutaneous and systemic diseases were associated with OLP patients. 3 patients had concomitant cutaneous lichen planus. Only 1 patient was found to be infected with hepatitis C virus. Various treatments had been tried by all patients. Oral squamous cell carcinoma developed in 1 patient at sites previously diagnosed by biopsy as OLP. Conclusion: This is the first clinical study of OLP patients in the Korean dermatologic literature. The clinical features of patients in this survey share many similarities with those reported previously, but showed some differences too. The clinical findings of OLP should be evaluated in much larger groups of patients and more experimental investigations should be conducted to find out exact pathogenesis and effective treatments for OLP.