Growth hormone-releasing hormone (GHRH) is limited as a diagnostic tool in both growth hormone (GH) deficiency and acromegaly. Measurement of a GHRH level may be helpful in patients with acromegaly suspected to have ectopic production of this peptide. The greatest potential of GHRH lies in its ability to be used as a therapeutic agent, either in GH-deficient states or, possibly, as an antagonist in acromegaly. Either a long-acting preparation or a preparation formulated to be active orally would greatly potentiate the clinical application of this peptide.