In order to determine the usefulness of ultrasonography (US) as a diagnostic tool for intra-abdominal disease of malignant lymphoma, US was compared with computed tomography (CT) as to the ability to detect an abnormality. The diagnostic accuracy of US and CT was evaluated on the basis of the overall outcome of the intra-abdominal disease, which was determined by serial studies of US, CT and other non-invasive diagnostic procedures, coupled with the serial measurement of superficial lymph nodes as an indication of changes in the intra-abdominal disease. Between September 1984 and February 1987, 158 echographic scan series were obtained in 58 lymphoma patients, among those, 56 instances of US imaging were examined concurrently with CT. In detecting the enlargement of the hepatic hilar nodes, CT showed a sensitivity of 73% and a specificity of 98%. For the splenic hilar nodes, CT showed a sensitivity of 50% and a specificity of 100%. Whereas, the sensitivity and specificity of US for the hepatic and splenic hilar nodes were all 100% for both sites, showing a trend favoring for US over CT. On the other hand, CT was somewhat superior to US in detecting the enlargement of para-aortic massses: CT showed a sensitivity of 97% and specificity of 100%, while US showed sensitivity of 71% and specificity of 100%. However, in detecting a mass to be composed of pathologic lymph nodes, US was more reliable than CT. US was almost comparable to CT in indicating the size of the liver and spleen. Finally, US and CT appeared to be supplementary in the imaging diagnosis of intra-abdominal disease of malignant lymphoma. US was also thought to be useful for the evaluation of tumor response to therapy.