Organic chemist Mary Peters Fieser was born in 1909 in Atchison, Kansas. Her father, Robert Peters was a professor of English at Midland College. The family later moved to Harrisburg, Pennsylvania when her father accepted a position at what is now Carnegie–Mellon University. Mary grew up in an environment in which reading and learning, as well as public service, were the norm. She and her sister Ruth graduated from a private girls’ high school that prepared them well to earn BA degrees from Bryn Mawr. Mary’s sister earned a Ph.D. in mathematics and became a university mathematics professor.

Louis Fieser, Mary’s future husband, was a chemistry professor at Bryn Mawr. She took all her chemistry classes from him and he became her mentor. Mary graduated from Bryn Mawr in 1930 with a BA in chemistry. Louis Fieser left Bryn Mawr that same year to join the faculty at Harvard University. Mary also decided to go to Harvard to pursue an advanced degree in chemistry. She carried out research half-time in his laboratory and also took courses. Mary had to officially enroll at nearby Radcliffe College in order to take chemistry courses at Harvard. Even then she was often not allowed to be in the laboratory with the male students, but rather had to carry out her experiments (without supervision) in a deserted basement of a nearby building. She was awarded her M.A. degree in chemistry in 1936 from Radcliffe College. She decided not to pursue a Ph.D. in chemistry.

Mary and Louis Fieser were married in 1932. They collaborated on the investigation of the chemistry of quinones and steroids. They developed synthetic procedures for the preparation of Vitamin K, cortisone, and the antimalarial compound lapinone. In addition to collaborating in the laboratory, Mary and Louis in 1944 published their first joint textbook, Organic Chemistry, which they had begun writing two years earlier. This text became very successful because of its originality in presentation as well as its excellent content and writing. It went through many editions, each always meticulously updated. Mary and Louis wrote several other texts. In 1967 they began to publish Reagents for Organic Synthesis and produced seven volumes before Louis died in 1977. Mary continued to publish these, sometimes with collaborators. In addition, the Fiesers published the Style Guide for Chemists in 1959.

Harvard University never granted a salary to Mary Fieser. She was, however, honored with the title of Research Fellow of Chemistry at Harvard about twenty-nine years after she began work there.

For her contributions to chemistry and chemical education, Mary Fieser was awarded the Garvan Medal in 1971. In 1996 Mary Fieser dedicated the Louis and Mary Fieser Laboratory for Undergraduate Organic Chemistry at Harvard University.

Mary Fieser died on March 22, 1997 in Belmont, Massachusetts.

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