The metyrapone test was applied to patients suffering from major depressive illness with melancholia, from mania, and from schizophrenia. Hypoactivity of the HPA axis as assessed by the test appears to occur infrequently in affective disorders and schizophrenia. High normal or exaggerated responses to metyrapone, as observed in Cushing's disease, appear to be correlated to DST non-suppression in melancholia.