Mass lesion at the submandibular region is quite commonly seen clinically, and there are many possible differential diagnoses. This paper presented a case we seen in December, 2003. The patient was a 60-year-old female with her right submandibular area asymptomatic swelling in ten days. Physical examination showed a fixed mass over submandibular region, and 4 × 3 cm in size. There is no obvious intraoral finding. Initial impression was right submandibular abscess or tumor. Biopsy was done and final diagnosis was plasmacytoma. Due to the patient living in Tauyuan, she was transferred to CGMH for further management.