The growth hormone-releasing hormone (GHRH) test was applied to more than 230 children. Twenty-five out of 61 patients with proven growth hormone (GH) deficiency responded to GHRH with a GH increase of greater than 10 ng/ml. In most of the patients with idiopathic GH deficiency, a priming procedure using daily injections of GHRH improved the secretory response to GHRH. Nearly all children with familial shortness of stature showed a prompt increase in GH levels, with a mean peak level of 34.9 ng/ml (range 0.5-144 ng/ml). A second test was performed in five children with familial short stature because of failure to respond to the first test. Children with constitutional delay of growth and development did not differ in their GH response from patients with familial shortness of stature. Ten girls with Ullrich-Turner's syndrome responded with a mean increase of 22 ng/ml GH (range 10.1-34.0 ng/ml). Therapy with glucocorticoids, as well as endogenous hypersecretion of cortisol, suppressed the responsiveness of the pituitary gland to GHRH. Suppression was also observed following a single dose of dexamethasone during the steroid-suppression test in eight obese children. Low responsiveness of the pituitary gland was also seen in patients with thalassaemia and transfusion-induced haemosiderosis. It is concluded that it is not possible to detect GH deficiency with a single GHRH test. A full endocrinological evaluation is necessary to prove the diagnosis.