 Increased sympathetic tone and subsequent diminished heart rate variability secondary to elevated circulating levels of catecholamines provides a possible pathophysiologic link between IHD and depression. For example, Carney et al 1988 have established the correlation of increased heart rate and decreased heart rate variability HRV in patients with major depression and IHD. Thus it follows that enhancement of sympathetic tone may be important in the independent development of IHD and major depression. The interplay among these systems remains to be investigated. The present study seeks to determine the relationship between major depression and sympathetic tone. 