 To date, no prospective clinical trial evaluating the efficacy of SJW for the treatment of tobacco use has been published. We propose to evaluate the efficacy of SJW for increasing tobacco abstinence and decreasing nicotine withdrawal symptoms in a randomized, double-blind, placebo-controlled, three-arm, parallel group, dose-ranging clinical trial. Participants N120 will be randomly assigned to one of the three groups and will receive a twelve-week course of SJW 900 mg per day, 1800 mg per day, or a matching placebo. 