Subclinical hyperthyroidism (SH) is defined as serum thyroid-stimulating hormone (TSH) below the lower limit of the reference range in the presence of normal free T4 and free T3 levels. Depending on the degree of TSH suppression, SH could be defined as mild (TSH, 0.1–0.45 mU/L) or severe (TSH< 0.1 mU/L). Patients with SH are often asymptomatic when symptoms are present, they are similar to the symptoms in patients with overt hyperthyroidism, although they are usually milder. The management of the SH is uncertain and should be individualized. We present this review after an extensive literature search and long-standing clinical experience. This review provides the prevalence, causes, clinical presentation, investigation, and therapeutic approach of SH in children.