ETHNOPHARMACOLOGICAL RELEVANCE: Ilex pubescens Hook. & Arn. is a traditional Chinese medicine for promoting blood circulation. Ilexsaponin A1 (IsA), a monomer of the compound, exhibits pro-angiogenic, anti-apoptotic and anti-inflammatory activities. Nevertheless, the pharmacological effects and specific mechanisms by which IsA affects platelets remain unknown. AIM OF THE STUDY: This study aims to investigate the antiplatelet effects of IsA and the underlying molecular mechanisms. MATERIALS AND METHODS: Platelet aggregation and ATP release were assessed using platelet aggregometry. Flow cytometry was employed to evaluate the exposure of P-selectin, integrin α RESULTS: IsA dose-dependently inhibited platelet aggregation and ATP release induced by collagen, U46619, thrombin and ADP. It also suppressed thrombin-induced P-selectin exposure and PAC-1 binding. Furthermore, IsA inhibited intracellular Ca CONCLUSION: IsA inhibited platelet function and thrombus formation. This has potential to be developed into a novel therapeutic agent for the treatment of thrombotic diseases.