A new development in the 20th century has been the increasing use of cigarettes manufactured primarily from flue-cured tobaccos. It has been clearly shown during the last 20 years that cigarette smoking impairs health to such a serious degree that means for its control must be developed. Cigarette smoking has been found to have a major part in the development of many diseases the most important of which are ischemic heart disease lung cancer chronic bronchitis and emphysema. Apart from these diseases which are major causes of death cigarette smoking is responsible for widespread and distressing disability from chest and heart diseases and increases the mortality and disability from several other conditions. The more recent adoption of cigarette smoking by women in developed countries is already associated with increasing mortality and morbidity from lung cancer and other illnesses. The health effects of smoking are largely confined to the individual smoker and although severe become manifest only after many years of smoking and are therefore not obviously connected with the habit. In countries where deaths and disability associated with cigarette smoking are already at high levels more preventive action is necessary. It is essential to take action that will promote the reduction or discontinuance of smoking and that will discourage young people from starting to smoke. Focus in the remainder of the discussion is on evidence connecting smoking with disease smoking habits and total mortality diseases causing excess mortality of cigarette smokers cigarette smoking as a cause of excess mortality cigarette smoking as a cause of excess morbidity specific diseases related to cigarette smoking approaches to prevention and experience in the United States.