Abstract: AIM:To investigate the value of echocardiography in the diagnosis of senile atrial septal aneurysm (ASA) in Tibetan patients on the Tibet Plateau. METHODS: Ultrasonographic results of senile ASA in Tibetan patients were retrospectively studied and ultrasonographic characteristics were summarized. RESULTS: ASA were found to be located at fossa ovalis in all 20 cases. By Olivares-Reyes A standard (Type I with aneurysm projecting into the right atrium, type II aneurysm projecting into the left atrium and type V aneurysm swinging with the cardiac cycle), nine cases (45%) were type I, 10 cases (50%) were type II and one case (5%) was type V. The average height and base diameter of type I and type II ASA were, respectively, (1.33±0.40) cm and (2.1±0.4) cm, and (0.85±0.22) cm and (1.5±0.3) cm. CONCLUSION: Senile ASA in Tibetan patients on the Tibet Plateau is most often located at the position of the fossa ovalis. Ultrasonography is the first-choice examination for diagnosis of senile ASA.