This study will investigate the multiple dose pharmacokinetics, safety, and tolerability of two dose strengths of varenicline in adolescents aged 12 to 16 years who regularly smoke at least three cigarettes per day.

Inclusion Criteria:

• Healthy male and female adolescents (12 - 16 years inclusive) with a total body weight greater than 30 kg who currently smoke an average of at least 3 cigarettes per day.

Exclusion Criteria:

• Male and female subjects with a positive urine drug screen and female subjects with a positive pregnancy test.