On March 25, 1986, the Surgeon General of the Public Health Service released a report that detailed the results of the first comprehensive, indepth review of the relationship between smokeless tobacco use and health. This review, prepared under the auspices of the Surgeon General's Advisory Committee on the Health Consequences of Using Smokeless Tobacco, is summarized in this article. In the United States, smokeless tobacco is used predominantly in the forms of chewing tobacco and snuff. During the past 20 years, the production and consumption of these products have risen significantly in marked contrast to the decline in smokeless tobacco use during the first half of the century. National estimates indicate that more than 12 million persons age 12 and older in the United States used some form of smokeless tobacco in 1985, and half of these were regular users. The highest rates of smokeless tobacco use occurred among adolescent and young adult males. Examination of the relevant epidemiologic, experimental, and clinical data revealed that oral use of smokeless tobacco is a significant health risk. This behavior can cause cancer in humans, and the evidence is strongest for cancer of the oral cavity, particularly at the site of tobacco placement. Smokeless tobacco use can also lead to the development of noncancerous oral conditions, particularly, oral leukoplakias and gingival recession. Further, the levels of nicotine in the body resulting from smokeless tobacco can lead to nicotine addiction and dependence.