The authors report a study in which they evaluate the efficacy of some laboratory parameters for monitoring intrasplenic hepatocyte xenotransplantation (mouse to rat) as an alternative to 99Tc-HIDA dynamic scan and histologic exam. Swiss mouse and wistar rat hepatocytes were obtained with collagenase digestion. Wistar male rats were used as recipient and were allocated into three groups: A) omotransplanted rats; B) xenotransplanted rats; C) xenotransplanted and immunosuppressed (Cyclosporin A: 20 mg/kg/daily orally) rats. All rats underwent > 70% hepatectomy. Blood samples were obtained daily from a femoral vein and AST, ALT, ALP, bilirubin, albumin and urea were measured. No statistical differences were observed among groups and the laboratory parameters tested can't be considered a valid technique to xenotransplant rejection monitoring.