One hundred and thirty-one consecutive requests for thyroid scintigraphy were analysed to assess their diagnostic contribution to the subsequent medical management of the patient. Forty one per cent of requests were to investigate the presence of a clinically detectable solitary nodule and, of these, one fifth had hot nodules. Diffuse goitres accounted for 38% of all referrals, but in only two patients (non-toxic hot nodule) did the results change management. A further 11% of referrals were for multinodular goitres and 8% for retrosternal goitres. In all cases of goitre no additional useful information was obtained from scintigraphy. It is concluded that thyroid scintigraphy was an unnecessary investigation in approximately 45% of cases. Its primary role was in the investigation of the solitary nodule and in detecting toxic nodules in thyrotoxic patients who had no evidence of Graves' disease. Greater discrimination of requests would avoid investigating patients unnecessarily and reduce costs.