Approximately 20% of patients with coronary heart disease (CHD) have major depression and 20% have minor depression at any given point in the course of their illness. Depression causes significant psychological and social morbidity, and is a risk factor for further cardiac morbidity and mortality. Although there are many possible biological and behavioral mechanisms, the causal pathways through which depression increases the risk for cardiac events and death are not well understood. Despite the morbidity associated with depression, and the devastating impact it has on the quality of life of patients with CHD, it is underdiagnosed and often left untreated. This article describes screening techniques for use in primary care and cardiology settings, and discusses the safety and efficacy of available treatments for depression in patients with CHD.