BACKGROUND Several reports about usefulness of probiotics, including Enterococcus faecium in the treatment of chronic hepatic encephalopathy in patients with liver cirrhosis have been recently published. The results obtained by the administration of Enterococcus faecium M-74 + selenium will be evaluated and compared with those published by Loguercio et al. for Enterococcus faecium SF 68. METHODS AND RESULTS Fifteen patients with liver cirrhosis, portal hypertension and chronic hepatic encephalopathy were treated, beside the standard therapy, also with one capsule of probiotic "Enterococcus faecium M-74 + Selenium" per day in three four-week periods, separated by two fortnight pauses. During the treatment, every patient was examined 9-times. The severity of chronic hepatic encephalopathy was evaluated with the aid of the portal systemic encephalopathy index, calculated from 5 parameters (mental stage, asterixis, number connecting test, blood ammonia, EEG). The indexes of initial and final values were compared. The time course of blood ammonia levels and that of results from number connecting test in either study were mutually compared on the basis of interval estimates of quadratic regression function. Significant improvement of the portal systemic encephalopathy index after the treatment was found: it decreased in average by 70% (55 to 85%, interval 95% confidence interval). The mental stage improved and the asterixis disappeared. The blood ammonia levels as well as the results from the number-connecting test after 8-9 weeks significantly approached the normal pattern. EEG findings improved and they were often normalised. Our starting blood ammonia levels (increased by 31% above norm) and results from the connecting test (increased by 60%) were significantly lower accordingly the Loguercio et al. (increased by 243 and 238%, respectively). During the treatment, the values in our study decreased by 25% and 30%, in the compared study by 50% and 70%. CONCLUSIONS Our results proved the hypothetical favourable effect of probioticum Enterococcus faecium M-74 + Selenium on chronic hepatic encephalopathy. Interestingly, a markedly higher relative therapeutic effect has been achieved in more serious disorder in comparison with the less severe disorders in the present study.