Both a prolonged QT interval and disturbance of autonomic nervous system function are markers of poor prognosis in patients with diabetes mellitus and alcoholic liver disease (ALD). We studied the prevalence of abnormal QT interval and autonomic nervous system dysfunction in 53 consecutive patients with end-stage liver disease before and after orthotopic liver transplantation (OLT). The maximum QT interval in any lead (QTmax) was assessed by two independent observers. The QTmax, corrected for heart rate (QTcmax) was prolonged in 44 patients (83%), although increased QT dispersion was not found. There was a significant correlation between the QTcmax and Child-Pugh score but not with etiology. Evidence of parasympathetic dysfunction was present in 41 patients (77%), and sympathetic dysfunction was present in 20 patients before OLT. Fifty-two patients underwent transplantation. There was significant improvement in the QTcmax interval after OLT (P < .001); 32 of the 44 patients with prolonged QTcmax (> 440 milliseconds) improved. Repeat testing was not performed in 7 patients, because they had died or had not undergone transplantation. Indices of parasympathetic function improved in 27 patients after OLT, but no improvement was observed in 8. Improvement in sympathetic dysfunction was observed in 13 of the 19 patients tested. There was no association between QTcmax, autonomic dysfunction, and survival. These results suggest that both prolonged QTcmax and some tests of autonomic function are temporary and arise as a consequence of liver dysfunction.