Indonesian Journal of Dentistry 2006; Edisi Khusus KPPIKG XIV: 22-24Lichen planus is relatively common inflamatory disorder which may have cutaneous and/or mucosal manifestation. The maglinant potential of oral lichen planus is still debatable. Some authors are sceptical about the premaglinant nature of the disease, while other investigators have reporterd that maglinant transformation occur in 1-10% of the cases. The aim of this study is to report a case of erosive oral lichen planus which shows maglinant transformation on histopatologic examination. A man of 39 years old visited the Dental Departement of Kariadi's Hospital with pain symptom of palatum, buccal and gingival mucosa both side for 6 months. On the physical examination shows the white lesions with striae configuration and pain, red erosive area inside on the palatum extends to the buccal mucosa and the gingival. The suspect dignose is erosive lichen planus, but the histopathologic examination shows epidermoid carcinoma. lt is concluded that erosive oral lichen planus has the potential to transform into epidermoid carcinoma.