Subclinical hypothyroidism (SH) is defined as an elevated thyroid stimulating hormone (TSH) associated with normal levels of free thyroxine. In obese persons prevalence of SH is significantly higher than in general population. SH is of particular interest in children with respect to the crucial role of thyroid hormones in the development of central nervous system and linear growth. Currently there is no general consensus on the treatment of SH with L-tyroxine. It is suggested that this hormonal state is rather a consequence that the cause of the overweight status.