It has long been hypothesized that posttraumatic stress disorder (PTSD) increases coronary heart disease (CHD) risk; however, empirical evidence is limited. In the first prospective study to date, individuals with higher PTSD symptom levels had a significantly increased risk for CHD, after controlling for known coronary risk factors. PTSD indicates a chronic stress reaction and is hypothesized to influence CHD either by causing biological alterations that lead to cardiovascular damage, or by leading to adverse health behaviors that increase CHD risk. A key issue is whether PTSD contributes to the development of CHD, if PTSD and CHD share common pathways, or if CHD causes PTSD. Research combined across different disciplines suggests that prolonged or chronic stress does influence the development of CHD. A better understanding of the relationship will increase prevention and intervention efforts. Cardiologists may be most effective when they can recognize and manage emotional distress in practice.