Background and Aims: Hepatic encephalopathy (HE) is a serious complication of cirrhosis. Electroencephalography (EEG) has been used in detection of HE but because of the subjective nature of the visual analysis its diagnostic value is questioned. Recently, a spectral analysis of EEG was proposed as a more accurate tool in evaluation of HE. We investigated the usefulness of spectral-EEG in detection of HE in patients with cirrhosis. Methods: Eighty two patients: 54 males and 28 females, aged 55±12 years (range 18–87) underwent neurological examination and closed-eye EEG, performed by one experienced neurologist. In 8 patients who underwent liver transplantation reevaluation was repeated in 5–24 posttransplant weeks. Spectral-EEGs was done on the transverse derivation P3-Pz/P4-Pz in the frequency range of 0.5–30Hz. Preselected 80–100s periods of artifact-free recording, split into 5s epochs were analyzed with Fast Fourier Transformation. Mean dominant frequency (MDF) was calculated and relative power of delta (0.5–4.0Hz), theta (4.0–8.0Hz), and alpha (8.0–13.0Hz) and beta (13.0–30.0Hz) rhythms were calculated. EEG results were then graded using the thresholds proposed by Amodio et al (J Hepatol 2008; 346–353). Results: Neurological examination identified 43 (52%) patients with overt HE: 22 (27%) in grade 1, 15 (18%) in grade 2 and 6 (7%) in grade 3 according to West-Haven criteria. We showed strong correlation between MDF and severity of liver disease in ChildPugh classification (p < 0.001) and ammonia levels (p = 0.02). EEG frequency showed no correlation with alcoholic etiology of liver disease. Patients with overt HE had significantly reduced MDF when compared with patients with unaltered neurological status (6.4±2.0Hz vs 8.0±2.3Hz, p = 0.001). We observed a reduction of MDF in patients with more severe HE. Seventeen (21%) patients without overt HE showed abnormal MDF and could be considered as having minimal HE. We observed a normalization of EEG frequency after transplantation (6.6±1.6Hz vs 9.1±2.1Hz, p = 0.02). Conclusions: In patients with cirrhosis, alterations in EEG were associated with the severity of liver disease, HE but not with the etiology of cirrhosis. They reversed after liver transplantation. Spectral analysis of EEG may offer an objective and valuable method in detecting, grading and monitoring of HE in liver cirrhosis. 655 REPRODUCIBILITY OF LIVER STIFFNESS IN CIRRHOSIS CAN AFFECT ITS ACCURACY FOR CLINICALLY SIGNIFICANT PORTAL HYPERTENSION DIAGNOSIS I. Yepes, D. Rincon, C. Ripoll, A. Fernandez, A. Matilla, M.V. Catalina, M. Salcedo, J. Miranda, G. Clemente, R. Banares. Liver Section, Hospital General Universitario Gregorio Maranon, CIBERehd-Hospital General Universitario Gregorio Maranon, Hospital General Universitario Gregorio Maranon, Madrid, Spain E-mail: ismayep@yahoo.com