We previously reported a method of intraperitoneal transplantation of liver cells attached to collagen-coated microcarriers, which resulted in prolonged survival and function of the transplanted cells. In the present study, we evaluated the efficacy of liver cell transplantation in providing metabolic support during acute liver insufficiency induced by 90% partial hepatectomy in rats. Ninety per cent of the liver mass (all lobes except the caudate lobe) was resected, and the rats were provided with 5% dextrose orally ad libitum upon regaining consciousness. This regimen results in severe hypoglycemia and death within 48 hr. When microcarrier-attached liver cells were transplanted into syngeneic and allogeneic recipients 3 days prior to 90% partial hepatectomy, significantly higher blood glucose levels were observed (p < 0.01), compared to the levels in control rats which received injections of microcarriers, liver cells or medium alone. There was a marked improvement in longterm survival (40% survived longer than 28 days; p < 0.001) in rats transplanted with microcarriers-attached cells. None of the rats given injections of microcarriers, liver cells or medium alone survived beyond 5 days. When liver cells alone or attached to microcarriers were injected intraperitoneally immediately after 90% partial hepatectomy, all rats became hypoglycemic and died within 48 hr, suggesting that vascularization of the transplant is required for function of the transplanted hepatocytes. The results indicate that intraperitoneal transplantation of microcarrier-attached hepatocytes prior to 90% partial hepatectomy in rats provides acute metabolic support resulting in improved survival.