Abstract: Chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD) not only have smoking as a common risk factor, they also share epidemiological relationships. There is good evidence to suggest that COPD is highly prevalent but under-diagnosed in CAD patients and vice versa. The symptoms of the two diseases can overlap, making differential diagnosis difficult. This highlights the importance of pulmonary function tests (PFTs) in patients with CAD, which is also a cardiological assessment in patients with COPD. COPD is a risk factor for the development of CAD independent of other cardiovascular risk factors and the presence of COPD worsens the prognosis in patients with CAD. Mechanisms underlying the associations between COPD and CAD have been less well studied, but inflammation is increasingly being recognized as an important factor linking the two diseases. Other potential contributors include increased oxidative stress, platelet activation and arterial stiffness. Physicians need to be aware of the important links between COPD and CAD, which helps to optimize the management of both conditions and improve patient outcomes.