Right atrial thrombus formation is a known mechanical complication of central venous catheter insertion, with an incidence of between 1.9% and 42%. There is an increased risk of thromboembolism following renal transplantation. However, a right atrial thrombosis is rarely reported in renal transplant recipients. Here, we report two cases of renal transplant recipients in whom a right atrial thrombus developed after kidney transplantation. One of them required surgery, whereas the other patient recovered after being given an anticoagulant therapy with warfarin.