This study is to evaluate the role of probiotics in the treatment of portal hypertension. In particular the role of probiotics on gut microbiota in liver cirrhosis patients will be studied and compared with cytokines and other substances implicated in the pathogenesis of portal hypertension. The hypothesis whether probiotics may change the prognosis of patients with portal hypertension will be studied. The hypothesis whether probiotics may halt the pathologic cascade of events leading to various complications (e.g. hepato-renal syndrome, spontaneous bacterial peritonitis, bleeding varices) will be reviewed.