Objectives The treatment of brain tumors in childhood is frequently complicated by growth retardation with a high proportion of irradiation (Irr)-induced GH deficiency (GHD) resulting in reduced adult final height (AFH) even after GH therapy (GHT). In order to optimize future GHT protocols, more information on the factors influencing the growth response to GH in these children is needed. This retrospective study evaluated AFH and influencing auxological and treatment factors of a standardized daily biosynthetic GHT in childhood survivors of brain tumors with documented GHD after brain Irr. Design and methods From the Belgian GH Registry, 57 children survivors of a brain tumor outside the hypothalamo-pituitary area with available AFH were stratified into two groups depending on cranial (C-Irr; n =25) or craniospinal (CS-Irr; n =32) Irr. Results In the C-Irr patients, results showed an AFH of −0.8 (−2.5, 1.4) SDS (median (range)) and in the CS-Irr patients, results showed a significantly ( P <0.001) lower AFH of −1.8 (−4.2, 0.0) SDS. AFH SDS corrected for mid-parental height (MPH) in the C-Irr group was −0.5 (−2.2, 0.9) and −1.5 (−3.6, 0.0) SDS in the CS-Irr group. AFH was positively correlated with age at end of tumor therapy, height SDS at start GHT, height gain SDS first year GHT, and negatively correlated with CS-Irr. Conclusions GHT failed to restore adult height to MPH in nearly half of Irr-induced GHD patients for brain tumor, especially those receiving CS-Irr, irradiated at a younger age or shorter at start GHT.