Smokeless tobacco usage, particularly by young men and boys, has increased dramatically in the United States. To assess their possible risk, we reviewed the records of 128 patients with oral carcinoma who had used smokeless tobacco exclusive of other carcinogens. Most were elderly white women (average age, 78 years), 78% of whom had used smokeless tobacco for 40 or more years. The median duration of symptoms before presentation was only 3 months, yet initially 42% of these patients had T3 or T4 lesions and 30% had nodal metastases. Forty-two percent had posttreatment recurrence at the presenting site (average, 8.2 months); 26% had a second oral-cavity tumor at a new site more than 24 months after treatment (average, 49.3 months), indicative of a field cancerization phenomenon. Forty-seven percent were alive after 3 years and 37% after 5 years. These findings emphasize that strong preventive programs are needed if today's young users of smokeless tobacco are not to form future oral cancer patient populations.