L-dopa in a dose ranging from 125–500 mg was given to 4 normal children and to 60 children with short stature (height < third percentile). Twenty-two of these 60 children were subsequently diagnosed as having GH deficiency on the basis of their response to L-dopa, arginine, and insulin, and on the basis of clinical findings. Of the 38 children with non-endocrine short stature tested with L-dopa, GH responses were also determined in 27 after arginine infusion and in 13 after insulin-induced hypoglycemia. No significant differences in peak responses to these stimuli were found. All of the normal children responded to L-dopa (GH > 6 ng/ml). Of the patients with non-endocrine short stature, 13.2% failed to respond to L-dopa, 14.8% failed to respond to arginine, and 15.4% failed to respond to insulin. All patients with deficient responses to either arginine or insulin exhibited normal responses to L-dopa; conversely, all patients in this group with deficient responses to L-dopa showed normal responses to one or both of the other stimuli. In contrast to the results obtained in this group, none of the GH deficient children responded significantly to L-dopa, arginine or insulin.