We compared the LA and LAA function parameters in patients with nonanticoagulated chronic nonvalvular atrial fibrillation with and without LV systolic dysfunction. Group I consisted of 12 patients with LV systolic dysfunction (mean age: 61+/-14 years; LV ejection fraction: 44+/-6 %), group II of 16 patients with normal LV systolic function (mean age: 52+/-15; LV ejection fraction: 65+/-3 %). LV ejection fraction (EF) was measured by echocardiography utilizing bi-plane Simpson method. The LA diameter was significantly larger in group I than group II (p<0.05). The LAA ejection velocity and LAA ejection fraction were sinificantly lower in the group I. (p<0.05). The PV systolic velocity and PV systolic velocity /diastolic velocity ratio were sisgnificantly smaller in group I (26.2+/-14.8 cm/s vs 51.5+/-22 cm/s, p:0.001; 0.7+/-0.6 vs 1.2+/-0.5, p:0.042; respectively). Although decreased LAA filling and PV diastolic velocities were determined in group I, this was not significant. These results indicate that both LA and LAA functions are prominently worse in patients with LV systolic dysfunction than in patients with normal LV systolic function.