A 61-year-old male patient with lichen planus with typical cutaneous and oral mucosal lesions is reported. The oral lesions became erosive and bullous. Various therapies were attempted without success. Finally, cyclosporin A was initiated in increasing doses up to 4 mg/kg per day. The previously therapy-resistant oral lesions resolved completely within 3 months. Cyclosporin should be considered as a therapy for serious erosive bullous oral lichen planus.