Growth hormone (GH) secretion assessment in the diagnosis of short stature presents certain problems in relation to the protocols designed for it and the interpretation of results. GH measurement in serum may be accompanied by IGF-I and IGFBP-3 measurements, and in some patients by GHBP measurement. Protocols for evaluating GH response to acute stimuli or spontaneous secretion are tedious, sometimes hazardous and difficult to interpret. This is due to the wide variation in responses observed in normally-growing children, to the age-dependent changes in these parameters and, in the case of GH, to the wide variation in immunoassay results. New techniques able to measure biologically-active GH molecules circulating in blood may help to simplify diagnosis. Severe idiopathic or organic GH deficiency poses no diagnostic problems. GH secretory insufficiency may be diagnosed as partial, idiopathic, isolated GH deficiency or as neurosecretory dysfunction. Clear cut-off values for these diagnoses and the possibility of a transient reversible pathology are not well established. Analysis of large series of children with different diagnoses in whom the growth pattern, either spontaneous or under rhGH treatment, final height and GH secretion re-evaluation at the end of growth were studied will help to clarify GH secretion or action abnormalities in these patients.