Dr. John Parascandola is an American medical historian. He served as the director of the American Institute of the History of Pharmacy from 1973 to 1981, as the Chief of the History of Medicine Division of the National Library of Medicine from 1983 to 1992, and as Public Health Service Historian from 1992 until 2004. Parascandola has taught at the University of Wisconsin-Madison and the University of Maryland. He is the author or co-author of several books, including "Doctors at the Gate: the Public Health Service at Ellis Island" and "Screening Syphilis: Dr. Erlich's Magic Bullet Meets the Public Health Service."