Abstract： Objective To investigate the safety and therapeutic effects ot a novel multi-layer flat-plate bioartificial liver (BAL) for patients with liver failure.Methods Thirty-eight patients with liver failure from Dec.2010 to Dec.2011 were treated with a novel BAL based on multi-layer flatplate bioreactor and the co-cultured cells of the porcine hepatocytes and mesenchymal stem cells.A total of 48 treatments was performed,4 h each time.The clinical signs and symptoms,liver function,ammonia,coagulation function and complete blood count were evaluated before,during and after the treatment.DNA in the collected PBMCs was extracted for PCR with PERV specific primers and the porcine specific primer Sus scrofa cytochrome B.The RT activity was detected as well.Levels of xenoantibodies (IgG,IgM) were determined by using ELISA kit. Titers of complement were quantified by CH50 kit.Results All treatment procedures were completed successfully without any adverse reaction. All samples presented negative PERV DNA and RT activity. The levels of antibodies were similar before and after treatment.Treatment was associated with a temporary decline in levels of complement,and then the levels were recovered quickly.The clinical symptoms such as acratia,anorexia and abdominal distension were improved.The stage of hepatic encephalopathy in 16 patients was decreased. The liver function and ammonia was reduced disproportionately. Seven patients in all were bridged to liver transplantation,2 patients died and 2 patients gave up the treatment,and the others were turned better.After the outcome judgment according to the standard developed by the Artificial Liver Group,and Chinese Association of Infectious and Parasitic Diseases,there were 9 patients with clinical healing,25 patients with improvement and 4 patients with no effect,and the cure-improvement rate was 89.5％.Conclusion The novel multi-layer flat-plate BAL could be used as a safe and effective therapy for patients with liver failure.