Normocytic-normochromic anemia (NC/NC) has been attributed to impaired bone marrow erythropoiesis in growth hormone (GH)-deficient patients. Moreover, the GH/insulin-like growth factor-1 (IGF-1) axis has been implicated in erythropoiesis regulation. In this retrospective multicenter study, we evaluated the incidence of NC/NC anemia in 279 children (196 boys), median age 10.52 years, with isolated idiopathic GH deficiency, and the effect of recombinant human growth hormone (rhGH) therapy on hemoglobin levels. At 6-month intervals, we recorded the Hb standard deviation score (Hb-SDS), the IGF-1-SDS, weight, height, and pubertal stage. Forty-one boys and 7 girls had NC/NC anemia before starting substitutive therapy (−2.59 SD). The Hb-SDS was significantly increased (P<0.05) after 12 months of rhGH therapy. The effect of rhGH continued up to 48 months (−0.39 SD), at which point all children had normal hemoglobin values. In conclusion, rhGH therapy resulted in normal hemoglobin values in all children enrolled in the study. These data support the concept that the GH/IGF-1 axis promotes erythropoiesis in vivo.