Objectives: To highlight the most characteristic histopathological findings of oral lichen planus and their correlation with the clinical manifestations and forms. Study design: We performed a retrospective study of 50 biopsied and diagnosed cases of oral lichen planus obtained over a period of 11 years, spanning from May 1998 to April 2009. We analyzed the age and sex of the patient, type of lichen planus, location and different histopathological findings, comparing them with the clinical lesions. Results: Seventy eight percent of the patients are female and 22% are male, with an average age of 56.06 years for both sexes. The most frequent clinical form is reticular, present in 78% of the cases, and the most common location is the buccal mucosa, present in 70% of the patients. Hydropic degeneration of the basal layer and lymphocytic infiltration in the subepithelial layer are observed in the entire sample. Signs of atypia were identified in 4% of the cases, but without dysplasic features. Other common histological findings were the presence of necrotic keratinocytes (92%), hyperplasia (54%), hyperkeratosis (66%), acanthosis (48%), and less frequently, serrated ridges (30%) and the presence plasma cells (26%). Conclusions: Oral lichen planus is a disease that is more common in women, usually appearing in the fifth and sixth decades of life. The most common clinical form is reticular, manifesting mainly in the buccal mucosa. Histological findings characteristic of oral lichen planus include hydropic degeneration of the basal layer, lymphocytic infiltration in the subepithelial layer and the absence of epithelial dysplasia; however, it is also frequent to observe hyperplasia phenomena at the epithelial level, hyperkeratosis, acanthosis and the presence of necrotic keratinocytes.