Inclusion Criteria:

1. at least 18 years of age;

2. smoking greater than or equal to 10 cigarettes per day for at least 6 months;

3. motivated to stop smoking.

Exclusion Criteria:

1. an unstable medical condition;

2. unstable angina, myocardial infarction, or coronary angioplasty within the past 3
months or an untreated cardiac dysrhythmia;

3. a personal history of seizures;

4. a history of closed head trauma with any loss of consciousness or amnesia in the last
5 years;

5. a history of closed head trauma with greater than or equal to 30 minutes of loss of
consciousness or amnesia or resulting in skull fracture or subdural hematoma/brain
contusion;

6. a history or psychosis, bipolar disorder, bulimia or anorexia nervosa);

7. current depression as assessed by Center for Epidemiologic Studies Depression
(CES-D);

8. active substance abuse other than nicotine;

9. used an investigational drug within the last 30 days;

10. current use of using a behavioral or pharmacologic tobacco treatment and unwilling or
unable to discontinue use;

11. current use of bupropion or varenicline in the previous 30 days;

12. current (past 14 days) use of antipsychotic or antidepressant;

13. an allergy to bupropion or varenicline;

14. untreated hypertension or baseline systolic blood pressure greater than or equal to
180 or diastolic greater than or equal to 100;

15. another member of their household already participating in this study.

16. All female subjects of childbearing potential who have a positive pregnancy test or
refuse to use contraception during participation in the study.