The role of vascularity as a prognostic factor was investigated in 35 patients undergoing arterial chemotherapy for liver tumours. Compared with parenchyma, tumour vascularity was classified as hot (18 cases), cold (12 cases), and mixed (12 cases) using 99mTc-macroaggregated albumin (MAA) hepatic arterial scans. The proportion of patients showing complete and partial responses to treatment was higher in the hot group (56 per cent) than in the combined cold and mixed group (12 per cent). In 15 cases (six hot, six cold and three mixed lesions), additional MAA scans were performed immediately after arterial embolization with degradable starch microspheres (DSMs). Either complete or partial reversal of tumour vascularity was observed after DSM-embolization in five and seven cases respectively, two and two of them respectively showing native cold lesions. As tumour vascularity appears to be a prominent prognostic factor, DSM-embolization should improve the efficacy of treatment by improving liver extraction of drugs and causing flow redistribution towards hypovascular areas.