B-scan ultrasonography was used as an aid in the evaluation of 15 human renal allotransplantations. Repeated studies detect changes in the kidney outline and the kidney cross-section, and the presence of abnormal acoustic interfaces in the perirenal areas. Over 70 studies were completed in this series. Of six cases of graft injection with functional, angiographic, radioactive isotope, and histologic confirmation, four showed a corresponding increase in size by ultrasonic laminography during the acute rejection phase, with reversal following correction of rejection. Seven cases of perirenal fluid collection caused by either lymph or other fluids were generally asymptomatic but were confirmed in four cases by subsequent clinical studies. They were initially discovered by this technique. Ultrasonic laminography is readily adaptable for the initial and follow-up evaluation of patients undergoing human renal allotransplants.