Recent research has confirmed that depression is a risk factor for the development and prognosis of coronary heart disease (CHD). Depressive symptoms are associated with the progression of underlying coronary atherosclerosis and clinical events such as acute coronary syndrome (ACS). Depression is poorly recognized and undertreated in patients following ACS, but progress is being made in developing abbreviated measurement tools that can be used in clinical cardiologic practice. Depressive symptoms emerging at various stages of CHD presentation may have different effects on CHD prognosis. The mechanisms mediating the relationship between depression and CHD include vascular inflammation, autonomic and endothelial dysfunction, and behavior patterns such as poor adherence to medication and advice. The optimal methods of managing depression following ACS have not yet been established.