Objectives: To evaluate the long-term effects of GH therapy in early diagnosed GH-deficient patients treated before 1 year of age. Study design: We studied all 59 patients (33 males) recorded by Association France-Hypophyse and treated with GH (0.50 Ϯ 0.15 IU/kg (S.D.) per week) before 1 year of age. Clinical presentation and growth parameters under GH treatment were analyzed. Results: Neonatal manifestations of hypopituitarism were frequent: hypoglycemia (n ¼ 50), jaundice (n ¼ 25) and micropenis (n ¼ 17/33). Although birth length was moderately reduced (¹0.9 Ϯ 1.4), growth retardation at diagnosis (5.8 Ϯ 3.8 months) was severe (¹3.5 Ϯ 1.9 standard deviation scores (SDS)). Fifty patients (85%) had thyrotropin and/or corticotropin deficiency. After a mean duration of GH therapy of 8.0 Ϯ 3.6 years, change in height SDS was þ3:11 Ϯ 2:06 S.D., exceeding 4 SDS in 19 patients. Only 9 patients (15%) did not reach a height of ¹2 S.D. for chronological age and 20 patients (34%) exceeded their target height. Pretreatment height SDS was independently associated with total catch-up growth. Conclusion: Conventional doses of GH allow normalization of height in patients with early GH deficiency and treatment.