Screening for distant metastases from head and neck tumors is still controversial. In the present study, the records of 1087 patients with newly diagnosed squamous cell carcinomas of the upper aerodigestive tract were reviewed retrospectively to determine clinical factors influencing the incidence and location of distant metastases. Overall, 130 patients (12.0%) developed clinical evidence of metastatic disease, 17 of whom (1.6%) had metastases at the time of initial presentation. The rate of distant metastases significantly increased with the initial stage of tumors (P < 0.00001) and the occurrence of local and/or regional recurrences (P < 0.00001) or of second primaries below the clavicles (P < 0.0005). The locations of primary cancers as well as histopathologic grading were not independent risk factors for the development of distant metastases. They mainly reflected different frequency distributions of stages. The lungs, liver and bones were the most common sites of metastatic disease, being involved in 68.5%, 23.8% and 20.0% of cases, respectively. Our findings show that at the time of initial presentation chest X-ray alone appears to be sufficient to exclude distant metastases from tumors classified as T1-3 NO. Further screening comprising abdominal ultrasound, bone scanning and/or CT scans of the thorax is particularly indicated for patients with advanced-stage disease, local and/or regional recurrences and second primaries below the clavicles. However, the individual decisions should consider whether the detection of distant metastases will significantly affect clinical management.