The purpose of the case report is to show that contrast enhanced ultrasound (CEUS) is an important imaging modality for patients with impaired renal function in detecting, characterizing and excluding renal cell carcinoma (RCC) in transplanted kidneys. To our knowledge this is the first report of CEUS in a tumour of a kidney transplant. CEUS is feasible, reveals comparable results to computed tomography and should be concerned as the method of choice for patients with impaired renal function like renal graft recipients.