Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function, atrio-ventricular node function and hemodynamics. Methods:Thirty-two Angora’s rabbits were selected and randomly divided into four groups. U1 group:urapidil 0.25 mg/kg; U2 group:urapidil 0.5 mg/kg; N1 group:nicardipine 10 μg/kg; N2 group: nicardipine 20 μg/kg. All these medicine were administrated within 30 seconds. Measurements were taken before and after the administration of urapidil or nicardipine for the follow-ing data: mean blood pressure(MAP), heart rate(HR), sino-atrial conduction time(SACT), maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT) , index of sinus node recovery time(SNRTI), Wenckebach A-V conduction frequency (WB), and P-R interval. Results:Significant MAP and HR changes were identified in all of the four groups before and after adminis-tration of both urapidil and nicardipine. No significant changes could be found in the rest of the parameters. Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P < 0.01); the MAP decreased(P < 0.01) and the HR increased drastically(P < 0.01). Conclusions:Neither urapidil(0.25 mg/kg, 0.5 mg/kg) nor nicardipine(10μg/kg, 20μg/kg) has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function. Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.