The purpose of the study is to measure the safety and efficacy of four dosing strategies of CP-526,555 for 12 weeks compared with placebo for smoking cessation. Post-treatment follow-up of smoking status to one year from randomization was performed in a non-treatment extension Protocol A3051018

Inclusion Criteria:

• Subjects must have smoked on average of at least ten cigarettes per day during the past year
• Subjects must have no period of abstinence greater than three months in the past year

Exclusion Criteria:

• Subjects with any history of clinically significant cardiovascular disease
• Uncontrolled hypertension