A case-control study in North Carolina involving 255 women with oral and pharyngeal cancer and 502 controls revealed that the exceptionally high mortality from this cancer among white women in the South is primarily related to chronic use of snuff. The relative risk associated with snuff dipping among white nonsmokers was 4.2 (95 per cent confidence limits, 2.6 to 6.7), and among chronic users the risk approached 50-fold for cancers of the gum and buccal mucosa--tissues that come in direct contact with the tobacco powder. In the absence of snuff dipping, oral and pharyngeal cancer resulted mainly from the combined effects of cigarette smoking and alcohol consumption. The carcinogenic hazard of oral snuff is of special concern in view of the recent upswing in consumption of smokeless tobacco in the United States.