Cigarette smoking is associated with increased overall morbidity and mortality. Smoking is a cause of cancer of the lung, oral cavity, larynx, bladder, and renal pelvis and a contributing factor in the development of cancer of the pancreas, stomach, cervix, liver, penis, and rectum. Smokers are at greater risk for coronary artery disease, cerebrovascular disease, and atherosclerotic peripheral vascular disease. Cigarette smoking is the single most important risk factor for chronic obstructive pulmonary disease and is associated with lower levels of FEV1 and increased respiratory symptoms and infections. Women who smoke during pregnancy have an increased incidence of complications, especially intrauterine growth retardation. Peptic ulcer disease is more common in smokers than in nonsmokers. Finally, involuntary smoke exposure is associated in adults with an increased incidence of lung cancer and possibly greater mortality rates from ischemic heart disease and in children with more frequent lower respiratory tract illnesses and reduced lung growth.