An atrial septal aneurysm (ASA) is a well recognized but rare cardiac defect where there is localized saccular deformity of atrial septum that bulges in to either right or left atrium. It may be present isolated or in presence of other defects. ASA can be diagnosed by tranthoracic (TTE) or transesophageal (TEE) echocardiography. In most situations it is diagnosed incidentally and often consider as benign entity. However, atrial arrhythmias and arterial embolisms are the complications ASA may present with. Here we present a 40 years male patient presents with right middle cerebral artery ischemic stroke with left sided hemi paresis, seizures and altered sensorium. All blood parameters and Doppler imaging showed normal study. Echocardiography revealed a moderate atrial septal aneurysm. Patient was treated with anti coagulation and discharged in stable condition.