The Authors analyse the main body of somatotropin function test: insulin hypoglycemia; arginine; ornithine; I-dopa; clonidine; galanin; GH-RH; physical exercise; sleep; combined stimuli; spontaneous GH secretion of varying duration. The advantages and disadvantages of the different tests are pointed out and some recent contradictory findings concerning the newest prolonged techniques are reported. The Authors claim priority for the clinical/auxological examination, with measurement of bone age and growth velocity and suggest the procedure for GH deficit diagnosis to be followed, also in the light of their personal experience.