The importance of continuing growth hormone therapy in the transition and adulthood periods must be studied in adolescents with growth hormone deficiency with childhood onset. Continuation of growth hormone therapy during the transition period in patients with permanent growth hormone deficiency is recommended as the therapy has positive effects on adult body composition and regional body fat distribution as well as its promotion of an increase in bone mineral content. The chance of having permanent growth hormone deficiency is higher in patients with a mass lesion involving the pituitary area, multiple pituitary hormone deficiency, isolated growth hormone deficiency associated with an identified mutation (i.e., growth hormone 1 (GH1) gene, growth hormone releasing hormone receptor (GHRHR) gene, sex determining region Y(SRY)-box 3 (SOX3) gene), midline defects, and congenital structural hypothalamo-pituitary disorders, such as an ectopic posterior pituitary; thus, such patients do not require retesting. The patients with idiopathic isolated growth hormone deficiency are recommended to undergo retesting. The most appropriate time for a retest is the age when the child achieves 98-99% of the adult height. The insulin tolerance test is preferred during the transition period and a threshold level of <5 ng/mL is recommended as the diagnostic criterion for complete growth hormone deficiency. Growth hormone doses higher than those used in adults (e.g., 70 mcg/kg/day) should be used until linear growth has been achieved. Decreased quality of life is another criterion for the initiation of therapy. This review addresses the definition of growth hormone deficiency and indications and usage of growth hormone therapy during the transition period.