The effect of intrasplenic hepatocyte transplantation (HTX) was studied in an experimental model of acute liver failure in rats with chronic liver atrophy. Rats underwent a portacaval shunt operation on Day -14 to induce liver atrophy, and underwent total hepatectomy on Day 0 as a start of acute liver failure. Intrasplenic hepatocyte or sham transplantation was performed on Day -7,-3, or -1 (n = 4 to 6 per group). During the period following hepatectomy, mean arterial blood pressure was maintained above 80 mm Hg and hypoglycaemia was prevented. Severity of hepatic encephalopathy was assessed by clinical grading and EEG spectral analysis, together with determination of blood ammonia and plasma amino acid concentrations, and "survival" time. Histological examination of the spleen and lungs was performed after sacrifice. Intrasplenic hepatocyte transplantation resulted in a significant improvement in clinical grading in all transplanted groups (p < 0.05), whereas a significant improvement in EEG left index was seen only in the group with transplantation on Day -1 (p < 0.05). In contrast to hepatocyte transplantation 1 day before total hepatectomy, rats with hepatocyte transplantation 3 and 7 days before total hepatectomy showed a significant 3- and 2-fold increase in "survival" time compared to sham transplanted controls: HTX at Day -1: 7.5 +/- 0.3 h vs. 5.9 +/- 0.6 h (p > 0.05), HTX at Day -3: 19.7 +/- 3.7 h vs. 6.5 +/- 0.3 h (p < 0.05), and HTX at Day -7: 13.8 +/- 3.2 h vs. 6.3 +/- 0.3 h (p < 0.05). Furthermore, rats with hepatocyte transplantation on Day -3 and -7 showed significantly lower blood ammonia concentrations after total hepatectomy (p < 0.0001). Histological examination of the spleens after sacrifice showed clusters of hepatocytes in the red pulp. Hepatocytes present in the spleen for 3 and 7 days showed bile accumulation and spots of beginning necrosis. The present data show that in a hard model of complete liver failure in portacaval shunted rats, intrasplenic hepatocyte transplantation is able to prolong "survival" time significantly 2- to 3-fold. The relevance of this observation for human application is discussed.