In most healthy individuals, dexamethasone suppresses adrenal cortisol production. However, in patients with depression, non-suppression frequently occurs. It is considered to be a hyperactivity of the limbichypothalamic pituitary-adrenal (LHPA) axis. To investigate a possible link between fibromyalgia and depression on the basis of response to dexamethasone suppression test (DST), we administered the DST to 20 fibromyalgia patients with depression, 26 nondepressive patients with fibromyalgia and 20 controls. In the fibromyalgia patients with depression. at the mean 16.00 hr, post dexamethasone plasma cortisol level was found significant (LSD: 0.655: p