We describe a randomized trial designed to evaluate the effectiveness of a smokeless tobacco cessation intervention delivered by dental hygienists as part of a patient's regularly scheduled cleaning visit. Seventy-five practices were randomized to continue their usual care (n=25; 239 smokeless tobacco using patients enrolled) or to receive training to provide a tobacco cessation intervention (n=50; 394 smokeless tobacco using patients enrolled). Patient reports indicated that the training program was successful in getting hygienists to implement the intervention. The intervention produced a strong effect on sustained quitting for smokeless tobacco users but had no impact on secondary outcomes, including unsuccessful quit attempts, future intent to quit using smokeless tobacco, and change in readiness to quit using. Frequency of smokeless tobacco use and receipt of specific components of the intervention, including the video and written materials, predicted sustained cessation. Since this intervention was delivered by dental hygienists as part of a patient's regularly scheduled cleaning visit, it is easily disseminable.