The tobaccosis denotes, collectively, all diseases resulting from the smoking, chewing, and snuffing of tobacco and from the breathing of tobacco smoke. This chapter talks about origin and peregrinations of tobacco, and nineteenth-century wars and tobaccosis. It also discusses twentieth-century cigarette tobaccosis, pathogenic mechanisms and nature of the tobacco hazard. Among the lower classes, pipe smoking was the common method of tobacco consumption; among the European upper classes during the 1700s, pipe smoking was largely supplanted by snuffing. Cigarette smoking is the most serious and widespread form of addiction in the world. The fabric of evidence that cigarette smoking is a major cause of atherosclerosis is woven of some evidential threads. First, the epidemic increase in ischemic heart disease in the United States during the twentieth century followed the rise in cigarette smoking and occurred particularly among those age-sex subgroups most exposed. Second, individual studies document a close relationship between heavy cigarette smoking and early coronary disease, among the others.