The aim of this study was to identify predictors of the growth response to growth hormone (GH) during the first 2 years of GH treatment, using auxological data and the maximum GH response (GHmax) to provocation tests. The patients were 169 prepubertal short children (27F, 142M), with Gmax values ranging from 0 to 65 mU/l. Their mean age (+/- SD) was 8.3 +/- 2.4 years (range 3-13 years), mean height SDS -3.0 +/- 0.7 (range -1.5 to -6.0 SDS) and mean pretreatment height velocity was normal (+/- 0.0 SDS) (range -1.6 to +0.9 SDS). The increase in height SDS during the first 2 years of GH treatment (0.1 U/kg/day) varied from 0.10 to 3.75 SDS, with younger children having a better growth response. Individual growth responses correlated (p