Dennis M. O'Connor, M.D.: 1942-2026

Dennis M. O'Connor, M.D.: 1942-2026

Dennis "Denny" M. O'Connor, M.D. (A&S '63, Med '67), professor emeritus of pediatrics at Saint Louis University School of Medicine, died Tuesday, Feb. 3, 2026. He was 83 years old.

O'Connor dedicated more than 50 years to pediatric care, specializing in treating children with cancer, blood disorders and infectious diseases.

O'Connor was born in St. Louis in 1942. He attended St. Louis University High School and then Saint Louis University for both college and medical school. After receiving his Doctor of Medicine in 1967, he completed an internship and residency in pediatrics at Cardinal Glennon Memorial Hospital (now SSM Health Cardinal Glennon Children's Hospital).

He then served a two-year military assignment to the Centers for Disease Control before returning to Cardinal Glennon and SLU for fellowship training.

"Dr. O'Connor was a superb pediatrician. He was not only knowledgeable, but his experience and clinical judgment made him the type of colleague you would go to if you were really concerned about a patient," said Aaron S. Miller, M.D., professor of pediatrics and chief of the Division of Pediatric Infectious Diseases at Saint Louis University School of Medicine and Cardinal Glennon.

O'Connor became an assistant professor of pediatrics in 1973 and was promoted to associate professor five years later. He served as director of the neonatal intensive care unit at Cardinal Glennon and was chair of pediatrics from 1977 to 1980 and vice president for medical affairs from 1991 to 1995.

"I will miss him enormously," said Barbara Whitman, Ph.D., professor of pediatrics at SLU School of Medicine. "Besides being the consummate colleague for decades, his office was next door to mine at one point and he held my hand through a year of treatment. He would make it a point to come into my office first thing every morning to make sure I was there and that I was OK. He was the best."

He also served as the chief of the divisions of both hematology/oncology and infectious diseases at Cardinal Glennon. He was a pivotal member of the Cardinal Glennon Board of Governors from 2012 to 2023.

"For half a century, Dr. O'Connor was the heart and soul of Cardinal Glennon, the fabric from which was woven the compassion, devotion, diligence and skill that comprise the backbone of our healing touch," said Andrew J. White, M.D., Robert W. Wilmott Endowed Chair of Pediatrics and a professor of pediatrics and pediatric rheumatology and immunology at SLU School of Medicine.

O'Connor helped create the Footprints Palliative Care Program at Cardinal Glennon, which strives to improve the quality of life of children living with pediatric cancer and other complex illnesses, as well as to coordinate support services with families. He served for years as the Footprints medical director, culminating with the SSM Health Cardinal Glennon Children's Foundation establishing the Dennis O'Connor Endowed Chair of Palliative Care.

"Because he knew SLU and Cardinal Glennon so well, he was able to provide the 'big picture perspective' on any issue. At the same time, his advice always seemed wise and down to earth," Miller said.

O'Connor's distinguished service in pediatric medicine was recognized in 2011 with the title of emeritus professor. Cardinal Glennon awarded him the Peter Danis Lifetime Achievement Award in 2015 and in 2019, the Glennon Award, which recognizes individuals or organizations who have made significant contributions to the health and welfare of children.

"He was a kind soul. He treated everyone he met with respect, which made him a wonderful physician, colleague and friend," Miller said. "Even after he retired, I would sometimes call him for advice about a challenging patient or career advice, and he was always helpful and supportive. I will really miss him."

Former colleague and professor of cardiac surgery at Saint Louis University Andrew Fiore, M.D., described him as a model human being.

"He was a complete physician, teacher and friend," Fiore said. "He was always totally dedicated to our hospital. I will surely miss him."

O'Connor is survived by his wife of 61 years, Beatrice (Giuliani) O'Connor; sons Patrick (Kathryn), Michael (Deborah), and Bryan (Alyssa); grandchildren Sean, Tommy, Nick, Maura, Sarah, and Nora; brothers Dan and Robert; nieces, nephews and cherished friends.

All services are private.