Background: About 3% of all cancer patients suffer from cancer of unknown primary origin. Generally, carcinoma of unknown primary (CUP) carries a grave prognosis, but primary tumor presented to the neck is exception to this. The aims of study are to determine the role of chemotherapy and to find the prognostic factors in unknown primary tumor presented to the neck. Method and Material: Eighty-four patients were diagnosed with unknown primary tumor presented to the neck between January 1996 and June 2002. Among 84 patients, 43 patients (52%) received chemotherapy, radiation or surgery were performed in 20 patients (23%), 21 patients (25%) had no treatment. Results: The response rates to chemotherapy were 87.5% in CUP only localized to the neck and 44.0% in CUP systemically involved (p=0.012). A median follow-up duration was 6.4 years and overall median survival time was 9 months. The median overall survival time of patients treated with chemotherapy were 17 months and that of patients who received surgery or radiation were 20 months (p=0.3548). The important prognostic factors were performance status and the number of involved organ. Conclusion: The prognosis of patients with CUP presented to the neck is more favorable than that of patients with CUP of other localization. The effectiveness of chemotherapy for CUP only localized to the neck was similar to that of surgery or radiation. The important prognostic factors were performance status and the number of involved organ.