Smoking remains the leading cause of Chronic Obstructive Pulmonary Disease (COPD), a leading cause of death and disability in New Zealand. COPD particularly affects Māori and Pacific people, given their higher rates of smoking. COPD patients tend to have a higher level of nicotine dependence and, as a result, often find quitting harder and are more likely to relapse back to smoking. A clinical trial is planned in Auckland to determine whether extended varenicline treatment combined with behavioural support can prevent relapse back to smoking in recent ex-smokers with COPD. Other outcomes of interest include changes in lung function and quality of life. Smoking cessation and relapse prevention are the most cost-effective interventions available for COPD patients that smoke, irrespective of their disease stage. The trial has the potential to significantly improve the outcomes of this common and chronic health condition in NZ.