Background: This study uses pulsed Doppler tissue imaging to investigate the effects of atrial fibrillation on right ventricular function and its association with other parameters of left heart function in atrial fibrillation patients. Methods: Twenty three patients with atrial fibrillation (AF) and 15 normal, age-matched control subjects underwent standard Doppler echocardiography including left atrial (LA) volume and pulsed tissue Doppler imaging (TDI) of lateral tricuspid annulus of right ventricle. Results: Between two groups, the ejection fraction, TDI of mitral annulus systolic (Sm), diastolic (Em) velocity and early mitral inflow to early diastolic tissue velocity ratio (E/Em) were not different. However, in the patients with AF, LA volume was significantly greater compared with the controls. In addition, systolic (St) and early diastolic (Et) TDI of lateral tricuspid annulus showed significantly lower value in the AF group. The Et��� showed significant correlation with the LA volume (r=0.614, p<0.001) among the other parameters. Conclusion: TDI of lateral tricuspid annulus of right ventricle would be reduced in the patients with AF and would be associated with LA volume, suggesting the presence of altered right ventricular function in these patients.