Thirty-nine patients with Hodgkin's disease (HD) with little or no clinical evidence of abdominal disease were investigated by abdominal CT scanning. The results were compared with those of bipedal lymphography and laparotomy and splenectomy. In the assessment of para-aortic lymph nodes, CT scanning and lymphography were of equal efficacy in determining the presence or absence of disease (87 and 79% respectively). Although CT scan could occasionally demonstrate disease in nodes in areas other than the retroperitoneum, its value was limited by its inability to detect involvement of nodes which were not significantly enlarged. CT assessment of splenic HD was unreliable, focal deposits being detected in only one of the 11 spleens involved. In this selected group of patients, CT scan had little advantage over lymphography in the description of disease extent. However, CT scan would appear to be the investigation of choice in patients with suspected abdominal relapse because of the more frequent presence of disease in sites not seen on lymphography. When treatment decisions are dependent on accurate knowledge of distribution of disease, CT scanning cannot yet effectively replace staging laparotomy and splenectomy as the means of achieving this information.