Guy R. Hasegawa received a B.A. in zoology from UCLA and a Doctor of Pharmacy degree from the University of California, San Francisco. After completing a residency in hospital pharmacy at the University of Illinois at Chicago, he worked as a clinical pharmacist at St. Joseph Mercy Hospital in Ann Arbor, Michigan, where he also served as Assistant Clinical Professor at the University of Michigan College of Pharmacy. From 1988 to 2019, he worked for the American Society of Health-System Pharmacists in Bethesda, Maryland, as an editor for the American Journal of Health-System Pharmacy. His pharmacy-related publications date back to 1978. He retired in 2019.
Dr. Hasegawa's research in Civil War medicine has dealt with diverse topics, including pharmacy, medical purveying, medical cadets, chemical weapons, and artificial limbs. He has published numerous historical articles in scholarly journals, contributed chapters to books, and coedited a collection of essays with James M. Schmidt.
Dr. Hasegawa is a member of the National Museum of Civil War Medicine (on board of directors, 2004-2016), the Society of Civil War Surgeons (Director Emeritus; on board of directors, 2002-2011), the American Institute of the History of Pharmacy, and the Society for the History of Navy Medicine .