COPD is concomitantly present in ~30% of patients with heart failure. Here, we investigated the pulmonary function test parameters for left ventricular (LV) diastolic dysfunction and the relationship between pulmonary function and LV diastolic function in patients with COPD.Overall, 822 patients who underwent a pulmonary function test and echocardiography simultaneously between January 2011 and December 2012 were evaluated. Finally, 115 patients with COPD and 115 age- and sex-matched control patients with an LV ejection fraction of ≥50% were enrolled.The mean age of the patients was 74.4±10.4 years, and 72.3% were men. No significant differences were found between the two groups regarding comorbidities, such as hypertension, diabetes mellitus, and anemia. The index of LV diastolic function (E/e') and the proportion of patients with high E/e' (defined as E/e' ≥15) were significantly higher in patients with COPD than in control patients (10.5% vs 9.1%, P=0.009; 11.3% vs 4.3%, P=0.046). E/e' was significantly correlated with the residual volume/total lung capacity ratio. Univariate and multivariate analyses revealed severe COPD (Global Initiative for Chronic Obstructive Lung Disease III or IV) to be a significant predictive factor for high E/e' (odds ratio [OR] 5.81, 95% confidence interval [CI] 2.13-15.89, P=0.001 and OR 6.00, 95% CI 2.08-17.35, P=0.001, respectively).Our data suggest that LV diastolic dysfunction as a complication of COPD may be associated with mechanical exclusion of the heart by pulmonary overinflation.