Inferior venacavography was used for revealing enlarged retro- or paracaval lymph nodes, some of which are not visualized by lymphography as they lay above L 2. As criteria for involvement of lymph nodes the dislocation or narrowing of the vena cava and the reflux of contrast medium in the lumbar veins were studied. Venacavography was carried out in 48 consecutive patients with lymphomas: 23 Hodgkin's disease and 25 non-Hodgkin's lymphoma. Signs of enlargement of paracaval lymph nodes were seen in 52% of patients with Hodgkin's disease and in 80% of the cases of non-Hodgkin's lymphoma. A fairly good agreement was found to between lymphograms and cavograms. Cavography proved to be an easy, inexpensive and minimally invasive technique that can be repeated several times without inconveniencing the patients too much, thus enabling restaging of patients after therapy; moreover, it produced fairly good urograms as the contrast medium is promptly eliminated through the kidney, thus eliminating the need for intravenous pyelography.