The recent introduction of sTSH assays allows for a definite control of the inhibition of TSH secretion. Clinical examination and serum thyroid hormone measurements are necessary to obviate hyperthyroidism. Relapses may occur after decades of apparent complete remission. Follow-up should be pursued throughout the patient's lifetime. Two specific means allow the detection of relapses at a stage when X-rays are still normal: measurement of serum thyroglobulin and 131I total body scan. Their combined use is recommended.