The association between cigarette smoking and the risk of cardiovascular diseases (CVD) is well established. However, the effect of other, less common, types of smoking on CVD risk, such as pipes and cigars in developed countries, remains uncertain. By contrast, in developing countries, a large panel of smokeless tobacco products are consumed alongside smoking products, with unknown effects on the risk of CVD. The aim of this thesis is to investigate the association between various forms of tobacco use with the risk of CVD in the setting of developed countries and of a developing country with a large population, Pakistan.