Jeffrey Ian Weitz is a Canadian hematologist, physician-scientist, and academic whose work focuses on thrombosis, hemostasis, blood coagulation, fibrinolysis, and antithrombotic therapy. He is a Distinguished University Professor with appointments in the Departments of Medicine, Biochemistry and Biomedical Sciences, and Bioengineering at McMaster University. He previously served as Executive Director of the Thrombosis and Atherosclerosis Research Institute in Hamilton, Ontario. His research ranges from laboratory studies of blood clot formation and dissolution to clinical trials of therapies for thrombotic disorders.
Education and training Weitz studied honors biology at the University of Ottawa before earning his medical degree, magna cum laude, in 1976. He completed an internship and residency in internal medicine at Toronto General Hospital, followed by a fellowship in hematology-oncology. From 1980 to 1982, he served as a research fellow at Columbia University’s College of Physicians and Surgeons in New York.
Career After his research fellowship, Weitz remained at Columbia University and Columbia-Presbyterian Medical Center, where he served as an assistant professor of medicine, an attending physician, and associate director of the coagulation laboratory.https://www.isth.org/news/672898/Jeffrey-Weitz-elected-as-the-new-ISTH-Secretary-General-for-2024-2028.htm He joined McMaster University in 1986 as an assistant professor of medicine, became an associate professor in 1988, and was promoted to professor in 1992. He later became a professor of Biochemistry and Biomedical Sciences and of Bioengineering. He has held several research and clinical leadership roles in Hamilton, including director of the Division of Thromboembolism at Hamilton Civic Hospitals, director of the Henderson Research Center, and Executive Director of the Thrombosis and Atherosclerosis Research Institute.
Research Weitz’s research examines the mechanisms of blood coagulation and fibrinolysis and their application to the prevention, diagnosis, and treatment of thrombotic disorders. His work has elucidated how anticoagulants and thrombolytic drugs act, including the resistance of fibrin-bound thrombin to conventional anticoagulant inactivation and the bleeding associated with tissue-type plasminogen activator. These findings have informed the development and clinical evaluation of newer antithrombotic therapies.
His research program spans basic biochemical research, experimental models of thrombosis, and clinical trials of antithrombotic drugs. He has authored hundreds of scientific publications and book chapters in hematology, cardiovascular medicine, and biomedical science.https://healthsci.mcmaster.ca/jeffrey-weitz-receives-prestigious-health-research-foundation-medal-of-honour/ Clarivate has recognized him as a Highly Cited Researcher, a designation for researchers whose multiple papers ranked in the top 1% by citations for their field and publication year in the Web of Science Core Collection.https://www.bohrium.com/en/scholar/e24964e6/Jeffrey_Weitz According to Google Scholar, his work has received more than 121,000 citations and has an h-index of 150 as of September 2026.
Professional leadership Weitz served as president of the International Society on Thrombosis and Haemostasis from 2020 to 2022. In 2024, he was elected secretary general of the society for the 2024–2028 term.
He has also served on editorial boards of journals, scientific committees, clinical trial steering committees, and research review panels. His academic work has included training and supervising medical students, residents, graduate students, and postdoctoral fellows.
Honour and awards Weitz received the Heart and Stroke Foundation of Ontario Career Investigator Award, which he held from 1992 to 2007, and the Heart and Stroke Foundation of Ontario/J. Fraser Mustard Endowed Chair in Cardiovascular Research from 2000 to the present. He held a Tier 1 Canada Research Chair in Thrombosis from 2001 to 2023. Weitz was elected a Fellow of the Canadian Academy of Health Sciences in 2005 and received the Research Achievement Award from the Canadian Cardiovascular Society in 2006.https://canadianhematologysociety.org/page/LifetimeAchievementAward He was elected a Fellow of the Royal Society of Canada in 2016. In 2019, he received the Ernest Beutler Lecture and Prize from the American Society of Hematology for excellence in translational research. The Canadian Hematology Society presented him with its Lifetime Achievement Award in 2022, and the American Heart Association named him a Distinguished Scientist in 2023. He was appointed an Officer of the Order of Canada in 2023 for contributions to the prevention, diagnosis, and management of clotting disorders, as well as for leadership and mentorship in thrombosis and hemostasis. He was invested in the Order in 2025. In 2025, he also received the Health Research Foundation Medal of Honour in recognition of his internationally acclaimed contributions to the prevention and treatment of blood clotting disorders.
Selected publications • Weitz, J. I., M. Hudoba, D. Massel, J. Maraganore, and J. Hirsh. “Clot-bound thrombin is protected from inhibition by heparin-antithrombin III but is susceptible to inactivation by antithrombin III-independent inhibitors.” Journal of Clinical Investigation 86, no. 2 (1990): 385–391. doi:10.1172/JCI114723.
• Weitz, J. I. “Low-molecular-weight heparins.” The New England Journal of Medicine 337, no. 10 (1997): 688–698.
• Agnelli, G., et al. “Oral apixaban for the treatment of acute venous thromboembolism.” The New England Journal of Medicine 369, no. 9 (2013): 799–808.
• Giugliano, R. P., et al. “Edoxaban versus warfarin in patients with atrial fibrillation.” The New England Journal of Medicine 369, no. 22 (2013): 2093–2104.
• Ruff, C. T., et al. “Comparison of the efficacy and safety of new oral anticoagulants with warfarin in patients with atrial fibrillation: a meta-analysis of randomized trials.” The Lancet383, no. 9921 (2014): 955–962.
• Pollack, C. V. Jr., et al. “Idarucizumab for dabigatran reversal.” The New England Journal of Medicine 373, no. 6 (2015): 511–520.
• Weitz, J. I., et al. “Anticoagulation with osocimab in patients with kidney failure undergoing hemodialysis: a randomized phase 2 trial.” Nature Medicine 30, no. 2 (2024): 435–442. doi:10.1038/s41591-023-02794-7.
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