Total hepatectomy was performed on 59 dogs divided into three groups. In Group A, comprising 17 dogs, the mean survival was 18.4 ± 5.8 hours. When auxiliary liver transplantation was performed immediately after total hepatectomy in 16 dogs, the mean survival was increased to 4.8 days. In Group C, when auxiliary liver transplantation was performed after the animals had been allowed to sink into hepatic coma, survival in 26 dogs was prolonged to 27 hours following hepatectomy (range, 14 to 67 hours). We conclude that the life of the comatose dog after total hepatectomy can be prolonged by the performance of a homologous auxiliary transplant. The technicalities of such a procedure and the rapid reversibility of the coma has been demonstrated. The reason for lack of long-term survival with this technique is at present not clear.