This article reviews the burgeoning literature on the relationship of mood disorders and heart disease. Major depression and depressive symptoms, although commonly encountered in medical populations, are frequently underdiagnosed and undertreated in patients with cardiovascular disease (CVD). This is of particular importance because several studies have shown depression and its associated symptoms to be a major risk factor for both the development of CVD and death after an index myocardial infarction. This review of the extant literature is derived from MEDLINE searches (1966-1997) using the search terms "major depression," "psychiatry," "cardiovascular disease," and "pathophysiology." Studies investigating pathophysiological alterations related to CVD in depressed patients are reviewed. The few studies on treatment of depression in patients with CVD are also described. Treatment of depression in patients with CVD improves their dysphoria and other signs and symptoms of depression, improves quality of life, and perhaps even increases longevity. Recommendations for future research are proposed.