Local and neck recurrences of squamous cell carcinoma of the head and neck (SCCHN) can mostly be detected early when the patient has regular follow-ups. Distant metastases though usually remain undiscovered until they produce clinical symptoms. Since Cyfra 21-1 correlates with the tumor size and stage in SCCHN, we looked for possible connections between Cyfra 21-1 increases and the development of distant metastases. The sera of 830 patients with SCCHN were tested for Cyfra 21-1. The levels were compared with the clinical run of the patients. When Cyfra 21-1 levels rose above the threshold of 3.3 ng/ml (71 out of 830) staging procedures were performed. Tumor growth was found in 50 out of 71 patients with elevated Cyfra levels (70.4%). Cyfra serum levels in those cases either represented development of distant metastases (27 out of 71), or local and neck recurrences. The results of this study show that Cyfra 21-1 is a suitable and helpful serological parameter for the follow-up of patients with SCCHN. In the event of an elevation of Cyfra 21-1 above the threshold during follow-up, we would recommend the performance of a thoracal CT-scan and abdominal omi ultrasound as staging procedures.