Sonograms of 59 cases of transplanted kidney were reviewed. The population consisted of 46 cases of successful transplantation and 13 cases of acute rejection. Sonographic spectra in cases of acute rejection were increased renal volume(69%), indistinct corticomedullary junction(69%), decreased renal sinus echo (62%), perinephric fluid collection(54%), sparse cortical echo(46%), areas of decreased parenchymal echo(31%), increased or decreased cortical echo(31%)and increased medullary pyramid index in 15%. These abnormalities were considerably uncommon in the cases of successful renal transplantation. Acute rejection is considered when three or more above abnormalities are present in the transplanted kidney.