INTRODUCTION Treatment of erosive oral lichen planus is difficult and often requires the use of systemic corticosteroids. This severe condition may lead to weight loss and impairment of patients' general condition due to painful oral erosions. The aim of this study was to evaluate the usefulness of thalidomide in the treatment of severe erosive oral lichen planus. PATIENTS AND METHODS The efficacy and safety of thalidomide were retrospectively evaluated in 6 patients with severe erosive lichen planus resistant or relapsing despite high doses of oral corticosteroids. Thalidomide was started at an initial dose of 50 to 100 mg/day and was then progressively decreased to the minimal effective dose. Follow-up evaluations were performed every two months by the same dermatologist. RESULTS Complete healing of erosive lesions was observed in 4 of 6 patients after a mean duration of 4 months. Partial epithelialization of erosive lesions, disappearance of dysphagia and weight gain were observed in one patient. Treatment failed in the last patient. The mean dose of prednisone of the 3 patients receiving both thalidomide and oral corticosteroids decreased from 37 mg/day at the beginning of the study to 7 mg/day at the end of the study. Two patients experienced severe side effects: phlebitis and neuropathy, leading to thalidomide discontinuation. Oral erosions rapidly relapsed after withdrawal of thalidomide. DISCUSSION Thalidomide seems to be an effective treatment of severe corticosteroid resistant and dependent or when systemic corticosteroids are contraindicated erosive oral lichen planus. Potentially serious side effects should restrict its use to the most severe forms of the disease.