A one-year, 9-month-old boy presented with pediatric head trauma associated with unusual accessory cranial sutures. Radiography demonstrated unusual bilateral longitudinal linear bone defects extending from the foramen magnum to the mendosal sutures, and bilateral transverse linear bone defects around the foramen magnum. No swelling or soreness were found in the occipital area, and there was no past history of head trauma. Therefore, the bone defects were considered to be accessory cranial sutures. Complex developmental patterns of the occipital bone and the considerable normal variation of sutures may simulate fractures around the foramen magnum. The present case of accessory cranial sutures is another example.