Ruth Levy Guyer is an American writer and commentator whose interests include medical ethics, environmental ethics, social justice, infectious diseases, narrative medicine, and public health.

Her first book, Baby at Risk: The Uncertain Legacies of Medical Miracles for Babies, Families and Society, was published in 2006. The book describes the ethical and social quandaries faced by parents, doctors, nurses, midwives, and family members when a baby is born gravely ill or prematurely. Guyer interviewed parents, hospital staff members, and others to understand how decisions are made on behalf of babies and considers how these dilemmas and their resolutions affect the family, the medical and nursing staff, and the wider society. Writer/surgeon Richard Selzer described the book as “a brilliant treatment of the conflicted emotions that come into play when a fragile infant comes into the world. ... Surely, it is the best work of its kind.” Bioethicist/physician/writer Jay Baruch said that “never before have I seen such an eloquent portrayal of the complex emotional terrain felt by families caring for such children ... a wonderful book.” Philosopher Robert Veatch characterized the book as “a beautiful, moving, passionate account” and noted that “obstetricians and their patients simply have to confront these issues.”

Guyer's second book, A Life Interrupted: The Long Night of Marjorie Day, was published in March, 2012. It is the true story about a brilliant and charismatic woman who lapsed into a coma and was gravely ill for seventeen years, then suddenly recovered and went on to lead a remarkable and unique life. The story is one that Guyer first heard more than thirty years ago from someone who was a good friend of Marjorie Day. The book threads together Day's amazing story with an account of Guyer's quest to find out what actually was wrong with Day, something that Day herself never learned.

Guyer’s essays, articles, reviews, commentaries, and stories have been published in a range of magazines, journals, newspapers, literary quarterlies, and books; her commentaries were a regular feature on National Public Radio’s weekend show All Things Considered for several years. Lists of these works and links to them are found at The Written Word and The Spoken Word.

Guyer has taught courses in bioethics, infectious diseases, writing, and other topics for many years to undergraduates at Haverford College, to graduate students at Johns Hopkins University, and to physicians and researchers at UCLA and the National Institutes of Health. A list of some of these courses and brief descriptions of their contents are found at Courses.

Guyer received a B.A. in biology from Bryn Mawr College and a Ph.D. in immunology from the University of California, Berkeley. She was a bench scientist for a number of years, then became a science writer, and eventually moved on to writing and speaking about bioethics, medicine, science, and other topics of interest––words, synchronicities, water, the sun, family lore, the wind, and so on––for the general public.

Developing a Reader's Guide to accompany the report of the President's Commission for the Study of Bioethical Issues: "Ethically Impossible" STD Research in Guatemala from 1946 to 1948.

Working on a collection of new essays in medical and environmental ethics.