Irving Lerner "Irv" Weissman M.D. (born Great Falls, Montana, October 21, 1939) is a Professor of Pathology and Developmental Biology at Stanford University where he is the Director of the Stanford Institute of Stem Cell Biology and Regenerative Medicine along with Michael Longaker.
Weissman was raised in Great Falls, Montana and started his scientific career at the McLaughlin Research Institute there. He obtained his MD from Stanford University in 1965 after earning a BS from Montana State University in 1961. His research has since focused on hematopoietic stem cell biology.
He developed methods to identify stem cells, and has extensively researched stem cells and progenitor cells. His research focus is "the phylogeny and developmental biology of the cells that make up the blood-forming and immune system." Weissman is widely recognized as the "father of hematopoiesis", in which he is the first to purify blood forming stem cells in both mouse and humans. His work has contributed greatly to the understanding of how a single hematopoietic stem cell can give rise to different specialized blood cells. Weissman is also a leading expert in the field of cancer stem cell, where his work has shed light on the understanding of the pathogenesis of multiple human malignancies. He is known also for transgenic research in which human brain cells were grown in mouse brains.
- Weissman, Irving L., American Men and Women of Science, Eds. Pamela Kalte, Katherine Nemeh and Noah Schusterbauer, Vol. 7, 22nd Ed. Detroit: Gale, 2005, p552-553. Gale Document Number: CX3454833983. Retrieved November 8, 2010
- "Faculty & Researcher Profiles - Irving Weissman". Stanford University Medical Center. Retrieved August 27, 2011.
- Irving Weissman, M.D. 2002 California Scientist of the Year
- "Biography Format for Board of Trustees' Agenda: A brief introduction of Irving L. Weissman, M.D." Retrieved November 8, 2010
-  Jim Lehrer News Hour interview with Irving Weissman, PBS, July 2005. Retrieved November 8, 2010