Oral lichen planus is a premalignant chronic inflammatory mucosal disorder with unknown etiology. It is a multifactorial disease and in addition to genetic background, infections, stress, drug reactions are suggested as risk factors. Helicobacter pylori which is involved in development of many gastrointestinal lesions may also be implicated in oral lichen planus induction. This is of clear importance for cancer prevention and the present study was performed to determine any association between H. pylori infection and oral lichen planus in southwestern Iran. Anti H. pylori IgG levels were determined in 41 patients and 82 sex-age matched controls. The results showed no association between H. pylori infection and oral lichen planus (51% in patients vs. 66% in control). or any of its clinical presentations.