It has been suggested that immunosuppression with cyclosporine induces marked sympathetic neural hyperactivity in heart transplant recipients. In the present study, the resting level of sympathetic nerve activity was investigated with intraneural recording in nine patients with severe chronic heart failure (NYHA class III-IV despite ongoing therapy), in nine heart-transplanted patients with previous heart failure (NYHA class III-IV) receiving standard low-dose triple-drug immunosuppression and in six age-matched controls without cardiovascular disease. Compared to the control group, resting sympathetic nerve discharge was markedly increased in heart failure patients (92 +/- 2 vs 60 +/- 6 B/100 b, P < 0.01), sympathetic nerve activity was lower in the majority of heart failure patients after heart transplantation, and mean burst incidence was significantly lower than in the cardiac failure group (70 +/- 7, P < 0.01). The difference between transplanted patients and the control group was not statistically significant. Thus, heart transplant recipients may reduce the augmented central sympathetic drive associated with cardiac failure despite ongoing cyclosporine treatment.