Regional chemotherapy, from a theoretical and pharmacological stand point, would seem to offer significant advantage over systemic therapy for the treatment of hepatic metastatic colorectal cancer patients. Clinical experience has shown us that the technique itself is fraught with practical problems, but over the years, specialist centres have learned to overcome many of these, making the technique safer and minimising the possibility of complications and toxicity. As a consequence, there is no doubt that high response rates can be achieved with HAI fluoropyrimidines. However, randomised data have only been obtained from small numbers of patients in suboptimally designed trials and, to date, true patient benefit in terms of either survival or quality of life has not been adequately demonstrated. In parallel with the U.S. Intergroup study, the U.K.-based MRC phase III clinical trial of regional versus systemic 5-FU/FA warrants urgent support and we would welcome collaboration with interested European and American centres. The outcome of this trial will fully define the role of HAI chemotherapy in the management of unresectable hepatic metastatic colorectal cancer, in the context of modern, modulated 5-FU.