The aim of this study is to evaluate the role of spectral electroencephalogram (EEG) analysis ((S)EEG) in quantitating brain dysfunction in cirrhotic patients, showing conditions of minimal hepatic encephalopathy (HE), and determining the impact of orthotopic liver transplantation (OLT) on its correction. (S)EEG was compared with visual EEG ((V)EEG) in 44 cirrhotic patients waiting for OLT and 44 healthy controls. Eighteen patients had overt HE, and 26 patients had no apparent HE. Twenty-one transplant recipients were reexamined 6 months after OLT. Computerized (S)EEG was performed by mean dominant frequency (MDF) and the occipital alpha-theta ratio, expressed as its logarithmic transformation (LogR). All patients underwent psychometric assessment. MDF and LogR correlated significantly with Child-Pugh score (P <.05) and the presence of HE (P <.0001). (S)EEG and (V)EEG determined minimal HE in 8 (31%) and 6 (23%) of 26 patients without overt HE, respectively. (S)EEG did not correlate with age, sex, cause of liver disease, portal hypertension, or psychometric test results. MDF and LogR improved in many transplant recipients. LogR was significantly lower in OLT candidates who died before OLT compared with OLT survivors. In conclusion, (S)EEG provides reliable quantitative information to evaluate the degree of HE and appears more sensitive than (V)EEG to discriminate a subclinical stage of HE. The improvement in (S)EEG results observed in transplant recipients confirms the reversibility of bioelectric brain dysfunction with restoration of liver functions.