We report a case of pleomorphic adenoma which was assessed pre-operatively as arising from the accessory parotid gland. Computed tomography (CT)-sialography provided information about the relationship between the tumor and the remaining normal accessory parotid tissue, and fine-needle aspiration of the tumor provided additional information as to the histologic features of the tumor, i.e. it was identified as of salivary origin. Zygomatic and buccal branches of the facial nerve extended over the accessory parotid gland tumor and the parotid duct was located just beneath the tumor. Therefore, pre-operative assessment of the tumor's nature was important for prevention of facial nerve damage and salivary fistula. The normal accessory parotid gland tissue associated with the accessory parotid tumor was histologically different from that of normal parotid gland tissue dissected in other patients with pleomorphic adenoma of the parotid gland. It is suggested that the difference in cell composition between these glands affects the development of the associated tumors.