Since most of the work discussed in this volume derives from experiments carried out in rats, the surgical techniques for orthotopic and heterotopic liver transplantation in that species are described in detail below. A method for rat liver transplantation was first described by Lee and Edgington 25 using the heterotopic auxiliary method in which both donor and recipient livers are subjected to partial (70%) hepatectomy. Modified methods were described by Korto et al. , 16 Hess et al. , 8 and most recently by Müller. 21 Orthotopic rat liver transplantation was first performed by Lee et al., initially using an extracorporeal shunt 17 and then without shunts. 18 In the Lee method, the donor and recipient portal veins were anastomosed end-to- end by suturing, and the donor bile duct was implanted directly into the recipient duodenum. A significant development was the anastomosis of donor and recipient bile duct, either via a single connecting tube inserted initially into the donor bile duct, 24 or by the connection of tubes inserted into both bile ducts (described below). 13