The incidence of solitary toxic adenoma of the thyroid in a general surgical unit with an interest in thyroid disease has been reviewed over a 15-year period. Six hundred and thirty thyrotoxic cases were treated surgically, 35 (5.6 per cent) having a solitary toxic adenoma. Thyroid enlargement or toxicity had been present for more than 5 years in 7 patients (20.0 per cent). Cardiovascular complications were present in 6 cases (17.1 per cent). Thyroid lobectomy resulted in 30 (85.7 per cent) euthyroid and 5 (143.3 per cent) hypothyroid patients. One toxic adenoma contained a focus of carcinoma. The clinical features, diagnosis and management of solitary toxic adenoma, and the management of symptomatic nodules which are 'hot' but not biochemically toxic, are discussed.