A 46-year-old man consulted to a private dental clinic for tooth extraction, where he was indicated to have abnormal shadow in the right mandible. The patient was referred to our clinic hospital. X-ray examination revealed an osteolytic lesion (3 x 2 x 1 cm), and tumor excision was performed. Pathological diagnosis was difficult. The tumor consisted of round cells with moderate atypia. Nuclear grooves were recognized. Immunohistochemistry showed positive CD1a and S100 protein. The Ki67 labeling was 16%. The author diagnosed the lesion as Langerhans cell histiocytosis (LCH). The patient became free of tumor, and discharged. However, the tumor recurred 5 years later. Two osteolytic lesions were found: one is mandible (3 x 1 x 1 cm), and another was maxilla (0.5 x 0.5 x 0.4 cm). Tumorectomy with wide margins were performed. The pathological diagnosis was LCH in both lesions. Whole body CT, MRI and PET were performed, but revealed no tumors. The patient is now free from tumor, and is followed up 7 years after the first presentation.