Objectives: Several studies exist on the left atrial appendage function (LAA) in permanent atrial fibrillation (AF). However, knowledge about the right atrial appendage (RAA) function is limited. We investigated RAA function with TEE and tissue Doppler imaging (TDI) in permanent AF patients with different etiologies and evaluated predictive parameters of right atrial spontaneous echo contrast (SEC) and thrombi. Methods: Patients with permanent AF developed due to three different etiologies (20 mitral stenosis, 44 hypertension, 20 hyperthyroidism) and 23 subjects with sinus rhythm were included into the study. RAA was examined with TEE and pulsed-wave and TDI velocities of RAA were measured. Results: Both PW-Doppler and TDI velocities were significantly impaired in all AF groups compared to controls. The lowest velocities were recorded in mitral stenosis patients. Right atrial moderate-severe SEC was observed in 75% of the mitral stenosis patients, in 25% of hypertensive patients, and in 30% of hyperthyroidism patients. Right atrial thrombus was observed in 25% of mitral stenosis, 4.5% of hypertension, and in none of the hyperthyroidism patients. In the multivariate analysis, the most important parameter associated with the severity of RAA SEC was the percent change in RAA area (B = -0.034, P = 0.03). Conclusion: In patients with permanent AF, impairment of RAA function and development of right atrial SEC-thrombus are closely related to the underlying etiology. These results suggested that evaluation of RAA functions may have an incremental value over the assessment of the LAA for determining thromboembolic risk. (Echocardiography 2010;27:384-393).