Sustained accelerated growth is necessary for GH-deficient patients to achieve normal mature heights. However, the catch-up growth seen during the initial 12-18 mos of standard GH replacement Rx (0.3 U/kg/wk) does not persist and few GH-treated children attain their full potential height. Previous studies of the dose/growth-response relationship have been confined to the initial phase of Rx. To assess the efficacy and safety of higher doses, given when catch-up growth had ceased, we gave GH for 8 months at 0.9U/kg/week to 8 GH-deficient children (7-12 yrs) earlier treated for 2-8 yrs with GH at 0.3 U/kg/wk. Mean growth velocity (GV) increased from 5.5±1.2 to 9.7±2.5 cm/yr (p