OBJECTIVE Continuous hemofiltration is an extracorporeal technique used to eliminate water and solutes by convective transport through a hemofilter. The aim of this study was to develop an experimental model of arterio-venous and veno-venous continuous hemofiltration in order to gain experience before its clinical application in human neonates. METHODS Twelve white New Zealand adult rabbits were anesthetized, tracheotomized and connected to a continuous flow neonatal ventilator. Continuous arterio-venous hemofiltration (n = 6) was performed via catheters placed in the carotid artery and jugular vein and veno-venous hemofiltration (n = 6) by a double-lumen catheter located in the inferior vena cava. Heart rate, arterial pressure, pH and blood gases, and the volume of ultra-filtrate were monitored and recorded for a three hour period. RESULTS In both groups a high rate of ultrafiltration was achieved. The volume of ultrafiltration decreased somewhat during the second hour and remained stable thereafter. No hemodynamic changes were detected. CONCLUSIONS The development of an experimental model for continuous arterio-venous and veno-venous hemofiltration in rabbits, facilitated the implantation of these techniques in human neonates. The model may be used to train the staff of the Neonatal Intensive Care Unit and to eliminate difficulties with vascular access and the care of extracorporeal lines.