Rosai-Dorfman disease is difficult to cure. In situ photoimmunotherapy combines local photothermal therapy with immunoadjuvant. In the present case report, a 39-year-old Chinese man with Rosai-Dorfman disease lesions below the left nostril and left preauricular region was treated with in situ photoimmunotherapy. The patient was treated with daily application of topical imiquimod (5%) and laser irradiations every 2 weeks for 8 weeks. After three cycles of treatment, the lesions improved markedly without adverse effects. Our results showed that in situ photoimmunotherapy can be used as an effective treatment for Rosai-Dorfman disease.