The authors report a case of monostotic eosinophilic granuloma which occured in the skull. A 37 year-old woman was presented with headache and soft mass in the occipital region. Plain skull X-ray showed a "punched out" osteolytic lesion in the right paramedian posterior parietal bone. Computed tomography shows a soft tissue mass and irregular bone destruction in corresponding region. On magnetic resonance image, the mass was of high signal intensity, with subgaleal extension and looks like a shirt stud or "collar button" on T2-weighted image. Total excision of the tumor and postoperative radiotherapy(1000cGy) were performed. The woman had no headache complains nor showed any focal neurologic deficit during the six months follow-up period. We report a case of monostotic eosinophilic granuloma of the skull with review of the pertinent literatures.