The pharmacokinetics of 5-fluorouracil (5FU) following its administration via the hepatic artery in conjunction with biodegradable albumin microspheres and angiotensin II have been studied. Peripheral venous concentrations of 5FU are lower and plasma clearance values higher following intrahepatic arterial administration compared with a similar dose administered by intravenous infusion over both 2 h and 24 h. For the 2 h drug infusions, plasma 5FU concentrations following co-treatment with angiotensin II and microspheres via the hepatic artery were intermediate between those of arterial and venous infusions of 5FU alone. There was a trend towards the peak plasma drug concentrations and the area under the plasma concentration-time curve (AUC) being significantly lower following co-treatment with angiotensin II and microspheres compared with intra-arterial and intravenous infusions of 5FU over 24 h. Co-administration of 5FU, angiotensin II and microspheres via the hepatic artery may reduce drug exposure in the systemic compartment and therefore may increase the therapeutic ratio of 5FU administration via the hepatic artery.