In a double-blind study, 20 patients with oral lichen planus were treated twice daily with 0.1% isotretinoin gel or the vehicle alone for two months. Subsequently, patients who used the placebo received the active preparation for another two months. Patients treated with the active medication displayed significantly greater improvement than patients receiving the placebo. Patients who were treated initially with the placebo showed statistically significant improvement after receiving the topical isotretinoin treatment for two months. Side effects from using the gel were primarily a transient burning sensation or irritation on initial application.