BACKGROUND Cigarette smoking is a well-known risk factor for development of coronary artery disease (CAD). However, some studies have suggested a "smoker's paradox," meaning neutral or favorable outcomes in smokers who have developed CAD, especially myocardial infarction (MI). OBJECTIVES The study aimed to examine the association of smoking status with clinical outcomes in the randomized controlled SYNTAX (SYNergy Between PCI With TAXUS and Cardiac Surgery) trial at 5-year follow-up. METHODS Detailed smoking history was collected at baseline, 6-month, 1-year, 3-year, and 5-year follow-up. The composite endpoints included death/MI/stroke (primary endpoint) plus major adverse cardiac and cerebrovascular events (MACCE) (combination of death/MI/stroke and target lesion revascularization) according to patient smoking status. The comparison of 5-year clinical outcomes between the groups according to smoking status was performed with Cox regression using smoking status at baseline or smoking as a time-dependent covariate. RESULTS A sizeable proportion (n = 322, 17.9%) of patients had changing smoking status during 5-year follow-up. One in 5 patients with complex CAD was smoking at baseline. However, 60% stopped after revascularization while others continued to smoke. Smokers had worse clinical outcomes due to a higher incidence of recurrent MI in both revascularization arms. Smoking was an independent predictor of the composite endpoint of death/MI/stroke (hazard ratio [HR]: 1.8; 95% confidence interval [CI]: 1.3 to 2.5; p = 0.001) and MACCE (HR: 1.4; 95% CI: 1.1 to 1.7; p = 0.02). CONCLUSIONS Smoking is associated with poor clinical outcomes after revascularization in patients with complex CAD. This places further emphasis on efforts at smoking cessation to improve revascularization benefits. (SYNTAX Study: TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries; NCT00114972) (C) 2015 by the American College of Cardiology Foundation.