INTRODUCTION There is still controversy for priming with sex steroid before growth hormone (GH) testing. OBJECTIVE We studied GH response to stimulation in 92 children >9 years with idiopathic short stature (height standard deviation score [HtSDS]-2). They were divided randomly into two groups. Children in Group 1 (n = 50) were primed with premarin in girls and testosterone in boys and those in Group 2 were not primed (n = 42). All children were tested using standard clonidine test and their serum insulin-like growth factor-I concentration (IGF-I). Additionally the growth and GH-IGF-I data of the two groups of children were compared with those for 32 short children (HtSDS <-2) below the age 9 years who were non-primed before GH testing (Group 3). RESULTS Neither GH peak response to provocation nor IGF-I concentrations differed between the two groups with and without priming. DISCUSSION Taking a cut-level of 7 ng/ml for normal GH response to clonidine, priming with sex steroids did not significantly increase the percentage of patients with normal GH response (52%) versus nonpriming (47%). IGF-I level did not show any significant difference among the two studied groups >9 years. The peak GH response to clonidine provocation test did not differ before (n = 42) versus after 9 years (n = 32) of age. CONCLUSIONS In this randomized study priming with sex steroids before GH testing did not significantly increase the yield of diagnosing short patients with normal GH secretion. In addition, GH response to provocation did not vary significantly between young (<9 years) and old (>9 years) short children.