Recombinant human TSH (rhTSH) (thyrotropin alfa, Genzyme Co.) has been developed to improve the management of patients with differentiated thyroid cancer, who need radioiodine (131I) for treatment or follow-up diagnosis. Data available from published series involving approximately 500 patients prove that rhTSH is safe and that mostly unspecific non-severe side effects may occur (e.g. nausea, vomiting, headache or fatigue and dizziness). Tumor swelling which has been occasionally observed after rhTSH injection is a phenomenon well known from the past attributed to endogenous TSH stimulation after thyroid hormone withdrawal (THW) and can be prevented or alleviated by concomitant administration of glucocorticoids. The absorbed dose to the tumor after preparation of 131I therapy with rhTSH as compared to THW is not statistically different. The radiation dose to the blood and the remainder, however, is significantly lower if rhTSH is used instead of THW which is a strong argument in favor of rhTSH. Most importantly, the quality of life (QOL) after rhTSH is preserved as compared to THW where symptoms of hypothyroidism significantly impair QOL. Last but not least, more convenient scheduling of patients and shorter duration of time to be spent in the radioprotective ward are further arguments in favor of rhTSH.