The U.S. Centers for Disease Control and Prevention (CDC) have extensive documentation on this topic.

In the introduction to this work, the CDC says:
”Smoking harms nearly every organ of the body; causing many diseases and reducing the health of smokers in general.1  The adverse health effects from cigarette smoking account for an estimated 438,000 deaths, or nearly 1 of every 5 deaths, each year in the United States.2,3  More deaths are caused each year by tobacco use than by all deaths from human immunodeficiency virus (HIV), illegal drug use, alcohol use, motor vehicle injuries, suicides, and murders combined.2,4  "

Visit www.cdc.gov/tobacco/data_statistics/Factsheets/health_effects.htm for more information.

References

1. U.S. Department of Health and Human Services. The Health Consequences of Smoking: A Report of the Surgeon General. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004 [cited 2006 Dec 5]. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/sgr_2004/index.htm.
2. Centers for Disease Control and Prevention. Annual Smoking-Attributable Mortality, Years of Potential Life Lost, and Productivity Losses—United States, 1997–2001. Morbidity and Mortality Weekly Report [serial online]. 2002;51(14):300–303 [cited 2006 Dec 5]. Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5114a2.htm.
3. Centers for Disease Control and Prevention. Health United States, 2003, With Chartbook on Trends in the Health of Americans. (PDF–225KB) Hyattsville, MD: CDC, National Center for Health Statistics; 2003 [cited 2006 Dec 5]. Available from: http://www.cdc.gov/nchs/data/hus/tables/2003/03hus031.pdf.
4. McGinnis J, Foege WH. Actual Causes of Death in the United States. Journal of the American Medical Association 1993;270:2207–2212.