In several reports a close relationship between lichen planus and chronic viral hepatitis has been demonstrated. According to the high prevalence of hepatitis B in communities like Iran and especially in Sistan-va-Baloochestan, a prospective study was performed for screening HBV markers in patients suffering lichen planus to detect the prevalence of HBsAg positive cases in them, comparing with general population, i.e. 4%. On the other hand we decided to detect some groups of lichen planus patients that this ratio mat be more in them. On this basis, 80 patients were studied during 9 months. 8 cases (10%) were HBsAg positive, showing significant increase comparing to the general population (4%). Also, the prevalence of HBsAg positive cases was greatly more in patients who had oral mucosal membrane involvement (41.2% of all patients).