A total of 221 consecutive early stage Hodgkin's disease (HD) patients were given mantle field irradiation only or in combination with chemotherapy in 1971-1991. In 1994 these patients responded to a mailed self-report questionnaire covering items on late medical symptoms. Of 200 patients (91%) who reported that their thyroid function had been tested, 110 patients (55% of those tested) had thyroid hypofunction at follow-up in 1994. Ninety-five patients (86% of patients with biochemical hypothyreosis) had started hormonal substitution. In 1993 and 1994, 101 of these patients who had received mantle field irradiation in 1980-1988 were called in for interview, clinical examination and thyroid function tests. Eighteen patients (18%) had started hormonal substitution treatment earlier, but 58 (70%) of the other 83 patients were found to have biochemical hypothyreosis. Of the 221 patients who completed the questionnaire, 66 patients (30%) reported dyspnoea on exertion for more than 3 years after treatment, 8 patients (4%) reported a history of myocardial infarction, 6 patients (3%) reported pericardial disease and 25 patients (11%) heart valve disease. Increased expenses incurred for dental care were reported by 106 patients (48%), increasing to 55% when Waldeyer's ring had been irradiated. The consequences of late sequelae after mantle field irradiation for future treatment are discussed.