Background Cor pulmonale is often associated with changes of structure and function of the right ventricle (RV) and thus further affects functional changes of the left heart. Our study aimed to assess the left ventricular (LV) and RV function in patients with cor pulmonale using high-definition CT (HDCT). Methods We prospectively studied 18 cor pulmonale patients determined by the pulmonary function test, clinical examination, chest radiograph, electrocardiogram, and echocardiogram. The subject group was compared to a control group consisting of 18 subjects. The RV and LV functions and RV myocardial mass (MM) were obtained by HDCT in the two groups. The results were compared between the two groups using the independent sample t test. Echocardiographic examination for cardiac function analysis was performed on the same day. Results The RV end-diastolic volume (EDV), RV end-systolic volume (ESV) and RV myocardial mass were significantly larger in the 18 cor pulmonale patients than in the control group (P<0.05). The right ventricular ejection fraction (RVEF) was significantly lower in the 18 cor pulmonale patients than in controls (P<0.01). The left ventricular EDV (LVEDV) and LVEF were significantly lower in cor pulmonale patients than in controls (P<0.01). There were strong correlations between MDCT and echocardiography, r(RVEF)=0.839 and r(LVEF)=0.916, respectively. Conclusions HDCT can accurately quantify RV and LV function. The right ventricular function is impaired in patients with cor pulmonale, while at the same time the left ventricular function is also impaired.