Eosinophilic granuloma is classified as a Langerhans cell histiocytosis. Although considered a rare pathology, up to 20% of all cases occur in the jaw bones, and radiographically may mimic odontogenic cysts or benign and malignant tumours. Different protocols have been suggested in the literature for treating eosinophilic granuloma. We report a case of polyostotic eosinophilic granuloma in a 34-year-old man showing ill defined mandibular and palatal radiolucencies. Due to the presence of multiple jaw lesions the treatment choice was chemotherapy. The clinical and radiographic feature are described, as well as treatment, complications and patient's follow-up.