Left atrial (LA) function plays an important role in the maintenance of cardiac output. However, whether assessment of regional LA myocardial dysfunction is useful for differentiating between CP and restrictive cardiomyopathy (RCM) remains unclear. Thirty-five patients with CP, 30 patients with RCM, and 30 healthy volunteers (controls) were enrolled in this study. The LA maximum volume (Vmax), LA minimal volume (Vmin), and LA volume before atrial contraction (Vpre-a) were measured using the biplane modified Simpson’s rule. All patients underwent two-dimensional speckle tracking echocardiography (STE). The peak systolic strain rate (SrS), early diastolic strain rate (SrE), and late diastolic strain rate (SrA) of the LA septum, LA lateral wall and superior walls were measured. The LA diastolic and systolic function was found to be reduced in patients with CP and RCM. The SrE in the LA superior wall and lateral wall were significantly decreased in patients with CP and RCM compared with controls (P < 0.001). The SrE of the LA septum in patients with CP was preserved compared to normal controls. Althouth the LA septal SrE in patients with CP was significantly reduced (P < 0.001). For the diagnosis of RCM, a cutoff value 1.40 for SrE of the LA septum showed a sensitivity of 94.7 % and a specificity of 89.7 %. The SrE in the LA superior wall and lateral wall were decreased while the LA septal SrE was preserved in patients with CP, indicating that the rigid pericardium might restrict myocardial motion and deformation in the lateral wall. The measurement of STE to determine the LA septal SrE can be helpful for differentiating between CP and RCM.