To define the adequacy of electron beam therapy in the treatment of N1-N3 head and neck cancer, 24 patients with primary head and neck cancers and N1-N3 cervical adenopathy received primary radiation therapy with or without chemotherapy for definitive control of their disease. All patients underwent computerized tomography (CT) to assist in the design of treatment to the posterior neck with electron beams after photon therapy to the level of spinal cord tolerance. Treatment with electrons to the posterior neck in patients with N1 disease was adequate in 92% (11/12) of patients. However, in patients with N2 and N3 disease, electron beam treatment failed, because of spinal cord tolerance problems, to cover the disease adequately in 92% (11/12). It is concluded that CT should be employed routinely in patients with N1-N3 neck disease to determine the proper electron energy prescription. For some patients, electron beam may not be appropriate, making it necessary to use individual planning to treat adequately the neck disease and avoid the spinal cord.