The etiology of eosinophilic granuloma remains an enigma. An unusual case of eosinophilic granuloma in a 7-year-old girl is reported. Throughout a 3-year period different foci of the disease were manifested in the osseous and gingival tissues of the four quadrants of the oral cavity. The lesions appeared consistently with the eruption of the permanent teeth. The primary lesions were diagnosed microscopically as a "mesenchymal tumor", "chronic nonspecific inflammation", and a "follicular cyst". However, histologic examination of the later developed lesions supported the diagnosis of eosinophilic granuloma with a possibility of evolution into Hand-Schüller-Christian's disease. Satisfactory control was achieved by curettage and radiotherapy.