In the past 10 years there has been an increasing interest in neuro-endocrinology as a way of assessing central nervous system processes, that might play a role in the development of psychiatric disorders. Partly as a diagnostic tool and partly for the more fundamental understanding of cerebral processes, growth-hormone (GH) stimulation tests have been tried. The GH responses to hypoglycemia, apomorphine, L-Dopa, clonidine, desipramine and amphetamine in psychiatric patients are described. There is a tendency for these tests to support a noradrenergic hypothesis for the pathogenesis of depression. The clonidine stimulation test seems particularly valuable in psychiatric practice, since it may be a trait-marker for depression.