From 1989 to 2005, 28 patients--20 men and 8 women--with cervical lymph node metastasis from an unknown primary carcinoma were treated and studied retrospectively. In histological diagnosis, open biopsy was conducted in 11 patients and non-open biopsy (FNA or frozen section diagnosis during surgery) in 17. Blind biopsy under general anesthesia was conducted in 10 patients, showing one primary tumor in the nasopharynx. Tonsillectomy for diagnosis was not done. In region of maximum-size lymph node metastasis, the upper cervical region accounted for 22 cases (79%). The N stage of cervical lymph nodes was as follows: N2a in 4, N2b in 14, N2c in 3, and N3 in 7. The histopathological diagnosis of cervical lymph node was as follows: squamous cell carcinoma in 21, adenocarcinoma in 3, mucoepidermoid carcinoma in 2, and others in 2. Therapy was as follows: only neck dissection in 7, neck dissection with postoperative radiation therapy in 13, and irradiation and chemotherapy in 8. All patients treated with irradiation and chemotherapy had been judged to be inoperable. Seven patients were found to have a subsequent primary tumor. Primary tumor sites were as follows: tonsils in 3 and upper gingiva, base of tongue, lung, and nasopharynx in 1 each. FDG-PET was conducted in 7 patients but revealed no primary tumor. Overall 5-year survival in this study was 46%. We should pay particular attention to the tonsils for detecting primary tumors in patients with cervical metastasis from an unknown primary carcinoma.