Cardiac masses represent a heterogeneous group, including secondary malignancies as the most common ones, followed by primary tumors, vegetations, and thrombi. Cardiac imaging techniques are essential for the non-invasive diagnosis of cardiac masses. Thrombi in a transplanted heart, especially in atria, are very common, but when they appear as multiple, they could be an early sign of rejection. We present the case of a cardiac transplant patient who presented with masses in both atria and the left ventricle, as well as symptoms of right heart failure. Various image techniques were useful in establishing the differential diagnoses and appropriate treatment.