Background/aim: The dried whole body of the leech Whitmania pigra, a well-known traditional Chinese medicine, has been widely used to treat thrombus diseases for thousands of years. However, its bioactive constituents were reported rarely. The aim of our study was to investigate antithrombotic components of it. Methods: The antithrombotic peptide was purified using a combination of anion-exchange chromatography, ultrafiltration and reverse-phase HPLC. the sequence of the peptide was determined using MALDI-TOF-MS-MS. Anti-platelet aggregation activity in vitro was evaluated using a turbidimetric method, and antithrombotic effect in vivo was assessed in an arterio-venous shunt thrombosis model in rats. Results: A novel antithrombotic peptide named WP-30, with the sequence VISRTQSNVQAAWGQV-GGHAADYSAVAIER, was isolated from the dried whole body of the leech W. pigra. WP-30 selectively inhibited thrombin-induced anti-platelet aggregation in vitro, and potently attenuated thrombus formation in rats in vivo. Conclusions: Taken together, we found a novel peptide from leech bodies, and this peptide showed antiplatelet aggregation and antithrombotic effects. (C) 2016 Elsevier Inc. All rights reserved.