Objectives: Metabolic syndrome (MetS) refers to a cluster of abdominal obesity, dyslipidemia, hypertension, insulin resistance that predisposes to cardiovascular disease. MetS affects more than 30% of adults in Korea and coexisting with COPD is frequent. Previous cross-sectional studies have suggested associations of impaired lung function with MetS. In contrast, several studies reported reduced all-cause mortality in obese COPD. The aim of this study was to explore whether MetS phenotype has different prognostic implications in COPD patients, particularly focusing on the rate of decline in FEV1 and SGRQ. Methods: A total of 189 eligible patients with COPD were selected from the Korean Obstructive Lung Disease (KOLD) cohort. The presence of MetS was defined according to the AHA/NHLBI criteria. The rate of annual decline in FEV₁and SGRQ were assessed between MetS (+) and MetS (-) group. The presence and number of exacerbation and mortality were also compared. Results: The prevalence of MetS was 32.3%. Patients with MetS (+) had lower FEV1 decline and lower SGRQ decline over 3-year follow-up. In multivariate analyses, MetS remained significant predictor of FEV1 and SGRQ decline independently of confounding factors (P=0.024, P=0.026, respectively). Number of exacerbation requiring hospitalization and mortality were significantly lower in MetS (+) group (P=0.037, P=0.012, respectively). Conclusions: MetS phenotype may relate to reduced deterioration of lung function and quality of life, and reduced exacerbation and mortality in Korean COPD.