Immunoscintigraphy with 111In-F(ab')2-anti-carcinoembryonic-antigen monoclonal antibody was performed in patients with primary head and neck tumours (n = 14), recurrences (n = 3) and suspected posttherapy lymph node metastases (n = 3). No false-positive but two false-negative results were obtained. Single photon emission tomography was performed 24 h after the intravenous administration of the radiopharmaceutical with a positive predictive value of 100% and a sensitivity of 90%. Only two very small (< 1 mm diameter) and necrotic primary tumours escaped detection, while the recurrences and lymph node metastases were always correctly diagnosed, in contrast to computerized tomography and ultrasound. Even though highly selective patients only were considered in the present research, the results do suggest that immunoscintigraphy may be usefully applied in all routine protocols for the study of head and neck cancer.