Aim:In the search for new antithrombotic drug candidates, the synthesis and anti-platelet activity of a new series of N-acylhydrazones that were designed as thrombin inhibitors has been previously described. The aim of this work was to further characterize the effects of these compounds on thrombin-induced platelet aggregation and induced thrombosis in vivo. Methods: In this work, four compounds were tested, LASSBio-693, 694, 743 and 752, on platelet aggregation induced by thrombin, ADP and TRAP-4A. These compounds were further tested using a mouse pulmonary thromboembolism model induced by collagen (500 μg/kg) and norepinephrine (80 μg/kg) or thrombin (2,000 UI), and a deep venous thrombosis model.