Several studies have been showed that rifaximin can improve cognitive functions, driving simulator performance and health-related quality of life in patients with minimal hepatic encephalopathy. The aim of this prospective randomized open controlled study was to evaluate the efficacy and safety of rifaximin at different doses for the treatment of covert hepatic encephalopathy.

Inclusion Criteria:

1. Patients agreed to sign the informed consents
2. Patients aged 18-70 years，males or females
3. Patients who were diagnosed with occult hepatic encephalopathy by PHES and Stroop tests

Exclusion Criteria:

1. Allergy to rifamycin/rifamutin/rifampin/rifapentine
2. Current or recent (<3 month) use of alcohol or can't stop drinking during the study period
3. Use of antibiotics within last 6 weeks
4. Use of lactulose/lactitol, probiotics, L-ornithine-L-aspart，zinc，metronidazole, neomycin, or rifaximin within last 6 weeks
5. Infection or gastrointestinal hemorrhage within last 6 weeks
6. Use of psychoactive drugs within last 6 weeks
7. Occurred overt hepatic encephalopathy within last 3 months
8. history of portosystemic shunt surgery or transjugular intrahepatic portosystemic shunt
9. Poor vision, color blindness or motor defects that interfere with the performance of psychometric tests
10. Other non-controllable neurological or psychiatric problems which may affect cognitive function such as Alzheimer's disease, Parkinson's disease or schizophrenia
11. Conformed or highly suspicious diagnosis of liver malignant tumors
12. Human immunodeficiency virus (HIV) infection
13. Uncontrolled hypertension, diabetes or other serious cardiac and pulmonary diseases
14. White blood cell count<1×10^9/L
15. Pregnancy and breastfeeding
16. Participated in other drug clinical trials within 3 months
17. The researchers thought it was not suitable for this clinical trial