The use of ultrasound "B" mode scanning in the diagnosis of enlarged retroperitoneal lymph nodes and other retroperitoneal masses was studied involving analysis of over 300 patients and controls. This method was found to be a useful procedure. Technical features and limitations, details of interpretation as well as diagnostic criteria are discussed. At the present stage of development, echographic study of lymphoma patients will outline almost all enlarged lymph node groups in the abdominal area and will add some areas not seen by conventional roentgen examination. In those patients who are considered for curative radiation therapy, both lymphangiography and echography are desirable in addition to other roentgen studies.