Squamous cell carcinomas (SCC) represent the vast majority of all malignant tumors of the head and neck. The development of distant metastases is now more often observed among these tumors than in the past. The department of Otolaryngology-Head and Neck Surgery, Free University Hospital has focussed upon the use of monoclonal antibodies (mAb) for treating SCC metastases. MAb E 48 was selected after it was shown to react strongly to SCC and minimally to normal tissues. In animal models clear tumor visualization and impressive tumor regression occurred when the antibody was linked to a suitable isotope. A diagnostic phase I/II study for the detection of lymph node metastases has entered 51 patients with head and neck cancer. Biodistribution data, acquired from surgical specimens, has shown an average tumor uptake of 30m%/g tumor tissue of the injected dose of mAb E 48. Extrapolation of data from therapeutic animal studies to these findings suggests that radioimmunotherapy can be effective in head and neck cancer patients, notably as adjuvant therapy in patients with a high chance of developing distant metastases.