Minimal hepatic encephalopathy (MHE), formerly known as subclinical hepatic encephalopathy, is the mild cognitive impairment commonly seen in patients who have cirrhosis. Current understanding suggests that MHE forms part of the spectrum of hepatic encephalopathy, although this remains to be proven. Although traditionally viewed as having negligible clinical significance, MHE has a significant impact on quality of life. MHE often goes undiagnosed because in many patients there is no evidence of clinically overt signs of impaired cognition. In addition, the diagnostic criteria for MHE have not been standardized, which means that the exact characteristics of MHE remain in question. This Review focuses on the pathogenesis and neuropsychological findings (incorporating neuroimaging) of MHE, as well as the effect of MHE on quality of life and survival, and developments in treatment.