A number of studies have evaluated the role of IGF1 measurement in the diagnosis of growth hormone deficiency (GHD). This study aimed to evaluate th e accuracy and the best cut-off of IGF1 SDS in the diagnosis of GHD in a large coho rt of short children and adolescents. One-hundred and forty-two children and adolescents with GHD ((63 organic/ genetic (OGHD), 79 idiopathic (IGHD)) and 658 short non-GHD chi ldren (median age 10.4 years) were included in the analysis. The two groups were subdi vided according to age (G1