BACKGROUND: Lichen planus is a multifactorial chronic in ammatory disease with diverse clinical manifestations involving the skin, hair, nails, and mucous membranes. OBJECTIVE: We evaluated the clinical effi cacy and adverse e ects of Bacillus Calmette-Guérin polysaccharide nucleic acid (BCG-PSN) injection, vitamin D injection, and the combination of both in the treatment of di erent types of lichen planus. METHODS: Thirty patients ranging in age from 12 to 70 years with clinically diagnosed lichen planus were enrolled in this study and divided into three groups according to treatment regimen. RESULTS: A partial therapeutic response in three patients and no improvement in seven patients were achieved in the intramuscular vitamin D injection group. Meanwhile, the intralesional injection of BCG-PSN was associated with complete response in three patients, partial response in three patients, and no response in four patients. The combination of both intralesional injection of BCG-PSN and intramuscular injection of vitamin D was associated with complete response in two patients, partial response in four patients, and no response in four patients. CONCLUSION: BCG-PSN alone appears to be effi cacious in the treatment of lichen planus, and vitamin D in combination with BCGPSN had no e ect on cutaneous lichen planus.