Dr. Lisa McMahon is a native of Charlottesville, Virginia. She graduated from the University of Virginia in 1992 then served as a Peace Corps Volunteer in Guatemala for 3 years. When she returned to the United States, she attended Texas A&M medical school and graduated in 2001. Dr. McMahon completed her general surgery training at Mayo Clinic - Arizona in 2006 and her pediatric surgery fellowship at Arkansas Children's Hospital in Little Rock, AR in 2008.

She is a member of many academic and professional societies including the Society of American Gastrointestinal and Endoscopic Surgeons, the Priestly Society, and the Arizona Chapter of the American Academy of Pediatrics. She is a Fellow of the American College of Surgeons and a Fellow of the American Academy of Pediatrics. In 2014, Dr. McMahon was named Section Chief of General Surgery at Phoenix Children's Hospital. Dr. McMahon was named Section Chief of General Surgery at Phoenix Children's Hospital and in 2021, she was elected to be the Chair of Surgery for the medical staff.

Dr. McMahon's medical interests include advanced laparoscopy, Hirschsprung's Disease, Pectus Excavatum, Slipping Rib Syndrome and Inflammatory Bowel Disease. She is the Director of the Chest Wall Anomalies Clinic and the Surgical director of the IBD clinic. Dr. McMahon is a co-chair of the Medical Advisory Committee for the Crohn's and Colitis Foundation of America/Southwest Chapter. She is also a member of the Pediatric Advisory Committee for the National Crohn's and Colitis Foundation. In her spare time, Dr. McMahon enjoys hiking, biking and reading.

She is fluent in Spanish and traveled to Central America in 2013 and Mexico in 2018 to provide medical care to underprivileged areas. Dr. McMahon performed pediatric surgeries in Rivas, Nicaragua, Guadalajara, Mexico, while helping to educate the local physicians and other medical staff in the latest surgical techniques.