Background: The treatment options for oral lichen planus (OLP) are numerous and include topical and systemic agents. Intralesional and systemic corticosteroids are used; however, the therapeutic results are often disappointing. Objective: To compare the influence of ozone, laser, and topical corticosteroid therapies in the treatment of OLP. Methods: One hundred twenty adult patients with 53 cm atrophic-erosive biopsy-proven OLPs in the tongue or buccal mucosa were recruited into the study. They were randomly assigned, by preoperative envelope drawing, to be treated with low-level laser therapy (LLLT group), ozone therapy (ozonated group), and topical corticosteroid therapy (positive control group). A placebo treatment containing base ointment without the active corticosteroid component was administered to patients in the negative control group. Response rate scores were determined on the basis of changes in the appearance score and pain score of the lesions between baseline and after each treatment. Results: The study subjects consisted of 56 male and 64 female OLP patients with a combined mean age of 42.6+/-8.3 years (range, 28 similar to 55 years). No statistically significant difference was detected in clinical severity among the groups. The sign scores decreased in almost all scoring groups; however, statistically significant improvement was found in the ozonated and corticosteroid-treated groups. Symptom improvement was achieved after treatment with LLLT, ozone, and corticosteroid (p<0.05). The efficacy indices were significantly higher in the ozonated and corticosteroid-treated groups. Conclusion: Ozone and corticosteroid therapies were more effective than 808-nm LLLT in the treatment of OLP.