Oral lichen planus (OLP) is a chronic inflammatory disorder which causes local irritation,discomfort and subsequent poor dentition and discomfort in eating . Various treatments have been suggested for OLP but their results are unsatisfactory .Despite the fact that steroids have been the main therapeutic choice for many years,some researches have been done regarding the efficacy of other medication such as metronidazole and doxycycline.The purpose of this study is to determine whether metronidazole and doxycycline are effective in the treatment of oral lichen planus and to compare their efficacy with each other.

Inclusion Criteria:

• a biopsy-proven untreated OLP of every type with no symptom.

Exclusion Criteria:

• pregnancy, presence of dysplasia in lesions,unilateral lesion suspected lichenoid reaction,history of drinking alcohol in at least 1 month prior to the study, smoking, systemic disease, use of systemic medications and hypersensitivity to the metronidazole and doxycycline.