This case report describes the effectiveness of the diode laser in treating lichen planus in a patient where the lichen lesion was resistant to local corticoids. The mucous lesion was treated with a 980 nm diode laser at about 2 W in continuous wave mode. The laser was guided with an optical fiber, diameter 600 µm. Based on the extension of the lesion, one to three applications were made after local anesthesia. The patient was placed in a two-year follow-up program. Regression and complete recovery of the lesion were observed. Based on these preliminary results, we suggest that this method is an effective therapeutic alternative to obtain both regression and control of oral lichen.