The purpose of the study was to measure the safety and efficacy of a 12-week flexible dosing strategy of CP-526,555 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 A3051019

Inclusion Criteria:

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

Exclusion Criteria:

• Subjects with history of clinically significant cardiovascular disease
• Subjects with uncontrolled hypertension.