Controversy continues to surround the management of differentiated thyroid cancer. For the past 20 years, a standardized protocol of total thyroidectomy followed by radioiodine ablation has been followed at Royal North Shore Hospital. During the period 1966-83, 327 cases of thyroid malignancy were treated surgically and, of these, 258 were differentiated thyroid cancer. Following total thyroidectomy, the incidence of recurrent nerve palsy was 2.8% and that of permanent hypoparathyroidism 3.2%. The overall 10 year cumulative survival for these patients was 87%. Whilst there were apparent differences in survival depending on the pathological type of tumour (papillary, follicular, mixed), further analysis shows that most of the differences in prognosis can be explained on the basis of age and sex alone. Young patients (less than 60 years) have an excellent 10 year survival (96%) whilst that for the elderly is only 61%. Males have a worse prognosis at 10 years than females. Total thyroidectomy is a safe procedure for the treatment of differentiated thyroid cancer. It allows the subsequent evaluation and treatment of unrecognized metastatic disease and offers the young patient a potentially normal lifespan.