The aim of work was to investigate effects of adenosine, AMP, GMP and ADP-ribose on bioelectric activity of bat heart. Purine nucleotides decreased action potential duration at level of 90% (APD90) repolarization in bat ventricular myocardium. When preparation of right ventricle was paced with frequency of 6 Hz, APD50 and APD90 were 7 +/- 2 ms and 60 +/- 5 ms, respectively. Adenosine decreased APD90 by 50 +/- 10% (n=6), AMP - by 30 +/- 10% (n=6), GMP - by 38 +/- 5% (n=6), ADP-ribose - by 24 +/- 6% (n=6) (concentration of all compounds - 10 ). Effects of purine nucleotides and nucleoside in bat ventricular myocardium exceed effects of same compounds in rat and ground squirrel ventricular myocardium. Inhibitory effects of purine nucleotides and adenosine in bat heart could be mediated by A1 adenosine receptors.