Purpose To investigate the effect of 5'-nucleotidase from Trimeresurus albolabris venom on platelet aggregations and its mechanism.Methods Piatelet aggregations induced by ADP,AA and PAF,respectively.were measured by turbidimetric method after platelet incubated with 5'-nucleotidase.Results 5'-nucleotidase significantly inhibited platelet aggregations induced by ADP,AA and PAF in a dose-dependent manner.Washed platelet inhibition experiment and the effect of Adenosine,CP/CPK on platelet aggregations showed that platelet aggregations inhibited by 5'-nucleotidase were associated with ADP hydrolysis and adenosine accumulation.The effect of ASA on platelet aggregations showed that the enzyme inhibited platelet aggregations probably by blocking the formation of TXA2.Conclusion 5'-nucleotidase from Trimeresurus albolabris venom inhibited platelet aggregations through ADP hydrolysis and adenosine accumulation,and maybe it is related to blocking the formation of TXA2.