To identify and describe late neurological complications in a Danish testis cancer cohort treated by radiotherapy. Clinical retrospective material of 94 consecutive patients with malignant testicular tumours treated at Aarhus County Hospital from 1964 to 1973. The irradiated dose in the paraaortic field varied from 27 to 55 Gy given 5 or 6 days a week, from the back and front alternately. The biological equivalent dose of the spinal cord was calculated using the linear-quadratic model. Median follow-up was 25 years, range 7 to 33 years. Seven patients were identified with late neurological complications after irradiation. One developed symptoms 9 months after treatment, but in the six other cases we found a latency period between 10 and 20 years from radiotherapy until the initial neurological symptoms began. The clinical picture in all seven patients was dominated by muscle atrophy, flaccid paresis in the lower limbs and absence of sphincter disturbances or sensory symptoms. High spinal cord dose was related to increased risk of neurological damage. During follow-up 19 patients developed another primary cancer in the radiation field; nine patients were diagnosed with severe arteriosclerosis and 13 patients with long-term gastrointestinal morbidity. Seven patients were identified with late neurological complications, and a clear dose-incidence relationship was shown. The latency period, from irradiation to the initial neurological symptoms began, ranged from 9 months to 20 years with progression of symptoms beyond 25 years. Furthermore many patients in the cohort suffered from solid tumours in the radiation field, severe arteriosclerosis and long-term gastrointestinal morbidity.