Abstract: Objective To determine the therapeutic effect of allogeneic umbilical cord blood stem cell transplantation in the treatment of patients with decompensated cirrhosis.Methods Total 50 patients of decompensated liver cirrhosis were included as follows:36 cases of liver cirrhosis based on chronic hepatitis B and hepatitis C, 12 cases of alcoholic liver cirrhosis, and 2 cases of biliary cirrhosis.The patients's Child-Pugh classification were as follows:2 (grade A) and 32 (grade B) , and 16 (grade C) .Stem cells were transplanted into the liver through liver artery catheter.Liver function and imaging examination of all the patients were checked after 2, 4, 12 and 24weeks of therapy respectively, while clinical symptoms and adverse reaction were observed.Results Symptoms were improved obviously after stem cells transplantation.Alb dropped transiently at 2 weeks from the mean value of 28.4 g/L to 26.3 g/L (P > 0.05) , but Alb increased to 37.3 g/L after 24 weeks (P < 0.01) .The mean value of ALT, AST, TBil dropped from 56.9 U/L to 46.3 U/L (P < 0.05) , 75.3 U/L to 50.0 U/L (P < 0.05) , 45.3 μmol/L to 31.2μmol/L (P < 0.05) respectively.PTA increased from 41% to 70% (P < 0.01) after 24 weeks therapy.Ascites disappeared in 36 patients, lessened in 5 patients, and no change in l case.The mean value of the largest cross-sectional area of liver CT scanning increased from 132 cm2 to 178 cm2 (P < 0.01) , and CT value from 52.6 down to 49.3 in the unenhanced CT scanning (P < 0.05) .Liver cracking narrowed.No adverse effects were observed in any of the cases.Conclusion Allogeneic umbilical cord blood stem cell transplantation in the treatment of decompensated cirrhosis is safe and feasible.The clinical symptoms and liver function and liver size of the patients were improved significantly with this therapy.