• The plasma norepinephrine (NE) level was measured in 45 depressed patients and in 41 normal control subjects. Patients who met DSM-III criteria for a major depressive episode with melancholia (MDE-MEL; N=16), and those with MDE but with melancholia in a previous episode (MDE-PMEL; N =8), had significantly higher levels of plasma NE than normal control subjects while lying and standing and a greater change in the levels; whereas, patients with MDE alone (N =10) and patients with dysthymic disorder (N =11) had levels of NE comparable with control levels. Bipolar patients (N = 7), all with current melancholia or a history of it, had significantly lower levels of NE while lying down or standing than depressed unipolar patients with similar histories of melancholia. Among unipolar patients with melancholia, nonsuppressors on the dexamethasone suppression test had significantly higher lying-down NE values than did suppressors, suggesting that dysregulation of both the hypothalamic-pituitary-adrenal axis and the peripheral sympathetic nervous system occur together in this subgroup of depressed patients.