Priming with sex steroids prior to growth hormone (GH) stimulation tests for the diagnosis of GH deficiency is still debatable. We analyzed the auxological data of boys with growth retardation who had normal GH responses to stimulation tests only after priming to establish the validity of priming in the diagnosis of GH deficiency. We also analyzed the effect of different protocols for priming and their efficiency in the diagnosis of GH deficiency. Fifty boys with growth retardation who failed to respond to unprimed GH stimulation tests but responded normally to primed tests were included in the study. Thirty-one of 50 boys responded to GH stimulation tests after single low dose testosterone, 11/50 boys after single conventional dose, and 8/50 boys with multiple-dose testosterone. The study group was followed till final height; height velocity, final height and height SDS were compared to parental and mid-parental heights to determine whether or not the children achieved their height potential. Mean final height SDS of the study group (-1.27 +/- 0.72 SDS) was similar to mid-parental (-1.38 +/- 0.72 SDS) (p = 0.249) and maternal height SDS (-1.26 +/- 1.05 SDS) (p = 0.941), whereas it was greater than the paternal height SDS (-1.7 +/- 0.86) (p = 0.001). The final height SDS of the study group was correlated to maternal, paternal and mid-parental height SDS. Height velocity after the test was greater than the previous height velocity. Final height SDS of the boys who responded to the GH stimulation tests with different priming protocols were compared and found to be similar. Normal responders in primed GH tests grow normally to their target height, suggesting that priming might be a valuable method in the assessment of GH status. Use of priming in the GH stimulation tests of peripubertal boys with decreased growth rate may help avoid unnecessary GH therapy. Multiple-dose testing might exclude GHD in a patient population who failed to respond to a single dose of testosterone. This finding suggests that multiple-dose testosterone might be a more valuable method for priming in the differentiation of normal from abnormal GH secretion.