Sixty-three hyperthyroid patients received ablative dosages of radio iodine. The efficacy of this treatment and the follow-up were assessed one to two and a half years later from case records and general practitioners. Fifty-seven percent of patients were hypothyroid at six months and 65% at one year; 4.8% had failed to become euthyroid within one year; 68.2% of patients were on thyroxine at the time of survey. Two patients had not been seen by their doctor for follow-up and one patient stopped her thyroxine. Most general practitioners preferred patients to be returned to their care once thyroxine treatment was stabilised. Rapid responses and predictable outcome are important advantages of this form of therapy over established methods of management. Intentional ablation is particularly convenient in situations where clinical and biochemical follow-up may be difficult. Good communications and a computer-controlled recall system should ensure effective follow-up.