Langerhans Cell Histiocytosis (LCH) is an uncommon benign bone tumour typically seen in children. LCH of bones in adults has been reported as solitary cases. The aim of the current study is to analyze different treatment approaches and the role of radiotherapy (RT) in adult LCH. Thirty patients from five Rare Network Cancer centers were included in this retrospective study. Median age was 30 years. The localization of tumours was skull bones in 12 (40%), lower extremity in 6 (20%), thoracic bones in 4 (133%), spine in 3 (10%), pelvis in 2 (6.7%) and multiple sites in 3 (10%) patients. Primary treatment was surgery in 1 (33%), surgery+ radiotherapy (RT) in 15 (50%), RT in 12 (40%), RT + CHT in 1 (33%) and corticosteroids in 1 (33%) patient. Median follow-up was 58 months. Complete remission was obtained in 21 (70%), partial remission in 4 (133%); 2 lesions were stable (6.7%) and progression was noted in 2 (6.7%) of the patients. Nine patients (30%) had recurrent disease. Recurrence rates were significantly lower in patients who were treated with surgery and RT (p < 0.003). Surgery plays a major role in the treatment of adult LCH of bones ; radiotherapy should be considered in the adjuvant setting and palliation.