At a median follow-up of 5 years, adjuvant razoxane (125 mg b.d.) given 5 days/week indefinitely following resection of colorectal cancer provided no benefit in terms of survival or recurrence for Dukes' A or B patients when compared to untreated controls. However in Dukes' C patients this treatment reduced the recurrence rate (P = 0.05) and possibly increased survival time (P = 0.08). Analysis now of the development of metastases in this trial which entered 272 patients over 7 years shows that in the Dukes' C group the incidence of liver metastases in the razoxane-treated patients is only about half that of the untreated patients (18 per cent versus 34 per cent) and that the time to first appearance of the liver metastases is twice as long in the razoxane-treated group as it is in the untreated group (80 weeks versus 40 weeks). It is concluded that the benefit of adjuvant razoxane observed in the Dukes' C patients is due to the antimetastatic activity of the drug in reducing and slowing down the development of hepatic secondaries.