Cigarette smoking is the leading preventable cause of death worldwide, and a considerable proportion of smoking-related fatalities are attributable to coronary artery disease (CAD). The detrimental effects of smoking span all stages in the development of CAD ranging from the early functional alterations in the endothelium and the microcirculation to the late clinicopathological manifestations of atherosclerotic plaques. Smoking results in the generation of free radicals and increased oxidative stress which plays a central role in the pathogenetic mechanisms leading to atherosclerotic disease. It causes reduced nitric oxide bioavailability and lipid peroxidation which are crucial initial steps of plaque formation. Furthermore, smoking enhances leukocyte and platelet activation and promotes local and systemic inflammation, which contribute to plaque progression and maturation. Finally, alterations in fibrinolytic and prothrombotic factors create a pro-thrombogenic environment which harbours the risk of plaque rupture and thrombosis. In smokers, the cessation of smoking is the most important intervention for cardiovascular risk reduction. Total mortality can be reduced by 36% which is comparable to established modern secondary preventive therapies. Nonetheless, non-aided cessation attempts are notoriously poor with a success rate of less than 10%. Patient counselling and pharmacological therapies are important aides for smoking cessation and can improve success rates by two to threefold. However, there is still need for improved strategies of smoking cessation to reduce the high socioeconomic impact of smoking.