The appropriateness of treating thyroid nodules with thyroid hormone is being debated: in fact, the development of nodules is not caused by an iodothyronine deficiency or a desuppression of TSH, and T4 seems to be able to regain control on cell proliferation. A very great number of authors have reported their experience with suppression of thyroid nodules with thyroid hormone, but treatment efficacy has been variably appreciated (9 to 69% regression). On the other hand, the four randomized prospective studies available at present, which analyze the evolution of nodules, especially on ultrasonography, have not demonstrated that hormone therapy is more effective than a placebo. The methodology of these studies is not free from criticism, and other prospective surveys are required, especially to establish whether this treatment is innocuous and whether some varieties of nodules may be more amenable to hormone therapy than others.