The dynamics of cognitive brain functions of 104 patients with both chronic non-cirrhotic (NC) and cirrhotic liver disease (C: C1, non-encephalopathic; C2, encephalopathic) were investigated by means of visual P300 potentials elicited in both the paradigms of transient (PI) and selective attention (PII). Conventional PVEPs, psychometric tests and quantitative liver function tests were also performed. As compared to both an age-matched control group (N) and the non-cirrhotic patients (NC), the N250 and P300 latencies of the cirrhotics (C) were equally prolonged in both P300 paradigms (P = 0.0001). By contrast, the P300 amplitudes were not different between the patient groups in either P300 paradigm. In the cirrhotics, however, the P300 amplitude differences between PII and PI (+ 3.7 +/- 2.8 muV, mean +/- 1 S.D.) were significantly (P < 0.01) smaller than in the non-cirrhotics (+ 7.5 +/- 5.2 muV) reflecting disturbances in the dynamics of visual attention. Interestingly, these P300 amplitude differences between both paradigms were positively correlated (r = 0.35; P = 0.005) with hepatic metabolic capacity, but not with liver blood flow (r = 0.23; P > 0.05). The diagnostic efficacy of the visual P300 in PI (sensitivity, 48%; specificity, 100%) was lower than that of the visual P300 in PII (79%; 100%) and that of the psychometric tests (63%; 94%), but it remained superior to that of the PVEPs (29%; 97%). It is concluded that in patients with cirrhotic liver disease visual P300 potentials can even reveal the dynamics of minor cognitive brain dysfunction and may also provide interesting pathophysiological information.