Twenty-five patients with liver metastases, chiefly due to colorectal cancer, were given a loading dose of razoxane for 3 days before 5 consecutive days of radiotherapy to the whole liver. Patients also took razoxane during the radiotherapy and then for one month afterwards. Liver tumour volume was measured on CT scans using the ELSCINT 3D soft tissue imaging programme just before and 4 weeks after the end of radiotherapy treatment. Twelve of the 25 patients had tumour volume reductions of more than 50%. The overall major response rate therefore is 12/25 (48%). In two of the major responders the liver metastases were due to recurrent stomach cancer. In addition to the 12 responders, four patients had a reduction of more than 20% but less than 50%, thus giving an overall response rate of 16/25 (64%). These results can form the basis of a formal, randomized, controlled clinical trial of radiotherapy alone (or any other treatment) compared with radiotherapy and razoxane in the difficult and life threatening condition presented by liver metastases.