An ex vivo perfused solid tumor preparation provides control over the physiological, biochemical, and pharmacological composition of the arterial input and easy access to the venous output. This is advantageous for studies of transport and metabolism in solid tumors. Here we present a tissue-isolated tumor preparation adapted to the nude mouse, allowing ex vivo perfusion of human tumor xenografts. Previously, such preparations have only been developed in rats, to study primarily rodent tumors. In the present study this new tumor preparation is physiologically characterized in comparison with subcutaneously transplanted tumors in nude mice using the human colon adenocarcinoma LS174T.