Patients with cervical metastases from an unknown primary tumour present both diagnostic and therapeutic problems. Twenty patients with a metastatic lesion in the neck, in whom the primary tumour was not found despite extensive, diagnostic procedures, were treated in the Department of Otolaryngology, Linköping University Hospital, during a 14-year period (1971-1984). Since 1975 tonsillectomy has been performed regularly on the affected side as a part of the diagnostic procedure. Eight patients without any clinical signs of a tonsillar primary have been diagnosed to have carcinoma by tonsillectomy and careful examination of the serially sectioned tonsillectomy specimen. The diagnosis of the metastatic nodes was based on histopathological examination in 8 patients and on fine needle aspiration cytology in 12. Four of 9 patients with squamous cell carcinoma survived 3 years and so did 4 of 5 with anaplastic carcinoma. All 5 patients treated surgically are alive and 6 of 12 who were irradiated. Ten of 12 patients with mobile unilateral nodes (N1) were alive at follow-up after 1-13 years but only 3 of 8 patients with fixed nodes (N3) at follow-up of 1-3 years.