Kidney tubules have previously been isolated from a number of different animal species using techniques involving perfusion and digestion of the organ with collagenase, followed by centrifugation of the resulting suspension. These techniques suffer from the disadvantages of requiring prolonged incubation with a potentially damaging enzyme and contamination of the preparations with glo-meruli. We have developed a procedure for the isolation of a purified preparation of rabbit kidney tubules without collagenase digestion. Rabbit or rat kidneys are perfused with buffer, followed by a suspension of magnetic iron oxide. The cortex is then homogenized by hand and put through nylon sieves of varying mesh sizes that separate large pieces of tissue from the glomeruli and tubules, which are caught on the smaller mesh sieves. The glomeruli containing entrapped iron oxide are then separated from the tubules with the aid of a magnet. Tubules isolated in this way are morphologically intact as shown by electron microscopy and have intact basement membranes in contrast to those isolated with the use of collagenase treatment. These tubules are equal to or surpass those isolated with the use of collagenase in metabolic functions such as oxidative metabolism and gluconeogenesis and in transport functions such as PAH and 2-deoxyglucose uptake. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.