Selegiline is a centrally acting sympatholytic agent with neuroprotective properties. It also has been shown to promote sympathetic reinnervation after sympathectomy. These actions of selegiline may be beneficial in heart failure that is characterized by increased sympathetic nervous activity and functional sympathetic denervation. Twenty-seven rabbits with rapid cardiac pacing (360 beats/min, 8 wk) and twenty-three rabbits without pacing were randomly assigned to receive selegiline (1 mg/day, 8 wk) or placebo. Rapid pacing increased plasma norepinephrine (NE) and decreased left ventricular fractional shortening, baroreflex sensitivity, cardiac sympathetic nerve terminal profiles, cardiac NE uptake activity, and myocardial beta-adrenoceptor density. Selegiline administration to animals with rapid ventricular pacing attenuated the increase in plasma NE and decreases in fractional shortening, baroreflex sensitivity, sympathetic nerve profiles, NE uptake activity and beta-adrenoceptor density. Thus selegiline appears to exert a sympatholytic and cardiac neuroprotective effect in pacing-induced cardiomyopathy. The effects are potentially beneficial because selegiline not only improves cardiac function but also increases baroreflex sensitivity in heart failure.