Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by acquired thrombophilia that leads to arterial/venous thrombosis. In patients with APS, stroke, transient ischemic attack, deep vein thrombosis, and pulmonary embolism are the most common thrombotic events. An intracardiac thrombus, a life-threatening complication with a high risk of increased morbidity and mortality, can occur in patients with APS, but it is rare. Still, it is treatable by intensive anticoagulant treatment and or surgical removal. In APS patients, spontaneous intracardiac thrombus formation is a possibility. With a preference for the right ones, however, thrombus formation can occur in all cardiac chambers. On native valves or mural endocardium, thrombus may occur spontaneously or cause by manipulations such as catheter positioning or prosthesis valves. It remains uncertain about the mechanism of thrombus formation. Here we reported 24-year-old lady who presented to the emergency department with shortness of breath and was found to have an intracardiac thrombus in the right atrium. She was admitted to the hospital and received enoxaparin warfarin, which she improved and discharged. In conclusion, while unusual, the probability of right heart thrombus co-existence should be considered in patients with APS who have pulmonary and cardiac symptoms. The prevention and management of