An animal model of acute hepatic failure which closely resembles human fulminant hepatic failure has been developed in rabbits with a view to testing the effectiveness of hemoperfusion through columns of various adsorbents as a means of providing temporary hepatic support. The model induced has the advantages of being: (1) non-hazardous to personnel, (2) reproducible, (3) potentially reversible and (4) closely resembling human fulminant hepatic failure in its clinical, electroencephalographic, serum biochemical and hepatic histological features. The ability of columns containing various adsorbents to extract potentially encephalopathic substances from plasma is being assessed. To overcome problems of biocompatibility a hemoperfusion system has been devised in which blood is perfused over a microporous polypropylene membrane and the dialysate passed through a column of adsorbent before recirculating over the membrane.