He graduated from high school in 1952. He received a Bachelor of Science from the University of Alabama in 1955 and an Doctor of Medicine in 1958 from the Medical College of Alabama.
He was an assistant professor and then associate professor of paediatrics at Baylor University between 1966 and 1975. During this time he became known for the co-implementation of the environmental bubble used to protect David Vetter from infection by external germs. In 1975 Montgomery became a full professor of paediatrics at University of Alabama School of Medicine, Hunstville campus, and in 1997 he became professor emeritus at the University of Alabama School of Medicine.
He interned at the University of Mississippi university hospital in Jackson, Mississippi from 1958 to 1959, and was a resident in paediatrics there from 1959 to 1960.
From 1960 to 1961 he served as a resident in paediatrics at Baylor University, after which he joined the United States military and served as the chief of Pediatrics at Seoul Military Hospital until 1963. He then returned to Baylor and from 1963 to 1964 he again served as a resident in paediatrics at Baylor University, and was a fellow in paediatric infectious diseases and immunology there in 1965.
In 1966 Montgomery became an assistant professor of paediatrics at Baylor, and was promoted to associate professor in 1970. He remained at the college until 1975 when he became the chief of paediatric programs and full professor at the University of Alabama School of Medicine Huntsville campus.
In 1997 he became a professor emeritus at the University of Alabama School of Medicine, where he has continued teaching medical students and serving on advisory boards.
Montgomery is best known for his assistance in the implementation of the first germ-free environmental bubble in the United States for newborn patients with no natural immune system. The first newborn patient to be placed in the bubble was David Vetter, who was placed in the environment soon after his birth under Montgomery"s care. The technology was initially supposed to be temporary, but had to be adapted over time by the Texas Children’s Hospital Team, which also included Mary Ann South and Joseph Wilson, in order to make it more permanent, including expansion into different rooms.
Vetter and Montgomery were featured in a January 1972 issues of Life Magazine soon after Vetter"s isolation.
Progress of Montgomery"s treatment was written about again in 1979 in The Decatur Daily. The patient died in 1984, and afterwards his life was the subject of a Public Broadcasting Service American Experience documentary featuring Montgomery.
The documentary featured the major points of Vetter"s life and complications, including Montgomery first breaking the news of the boy’s diagnosis soon after he was born. Montgomery served as his physician until 1975 when he moved from Baylor to the University of Alabama.
He has also researched congenital rubella syndrome and transplant rejection in heart transplant patients.
He has also published more than eighty academic articles
He is a member of Phi Beta Kappa. Montgomery has been a member of the American Association of Immunologists, the Infectious Diseases Society of America, the International Experimental Hematology Society, the Society of Paediatric, and the New York Academy of Sciences.