In this study, after consenting, subject is screened for study eligibility. If they pass the study screen, they are randomized to study drug (800 mg/day of SAMe, 1600 mg/day of SAMe or placebo-look-alike). Subjects will stay on their assigned dose for 8 weeks with weekly (visits 3-6) or biweekly (visits 7-8) clinic visits. After the 8 weeks of medication, they will receive a phone visit at week 16 and then a final visit at week 24. Study participation ends at the week 24 visit. During study participation, subjects will undergo counseling at every study visit based on the counseling manual, Smoke Free and Living It. They will also keep diaries (record of daily withdraw symptoms and tobacco use) for the 8 weeks while on study medication. At each study visit, smoking and safety outcomes are measured.