Mohsen Ziai, an Iranian native who represented the eighth generation of his family to pursue a medical career and who played a crucial role in the growth of what is now Inova Children’s Hospital in Fairfax County, died March 27 at his home in Great Falls. He was 85.

The cause was pneumonia, said a daughter, Fatemeh Ziai.

Dr. Ziai, a specialist in pediatric infectious diseases, was a leading medical administrator in Iran before moving to the United States in 1977 to serve as chairman of pediatrics at Rochester General Hospital in New York and a professor of pediatrics at the University of Rochester.

For much of the 1980s and 1990s, he was a professor of pediatrics at Georgetown University and chairman of pediatrics at what was then Fairfax Hospital. At Fairfax, he was credited with transforming the pediatrics department by vastly expanding its medical specialties, training programs and academic affiliations.

“He saw the potential 30 years ago,” said Stephen Keller, who worked under Dr. Ziai for 17 years and is now medical director of the Inova Children’s Hospital’s pediatric intensive-care unit. “He was recognized as a visionary leader who was charismatic and had a great academic reputation and could develop the program at Fairfax. He was widely acknowledged as the founder of our children’s hospital.”

Mohsen Ziai, an Iranian native who was the eighth generation of his family to pursue a medical career and who played a crucial role in the growth of what is now Inova Children’s Hospital in Fairfax County, died March 27 at his home in Great Falls. He was 85. (Courtesy of Inova)

When Dr. Ziai arrived at Fairfax, his department was small and overshadowed by other local pediatric centers. Beds were often removed to serve adult patients in other units, and the very sickest children were sent to Children’s National Medical Center or Georgetown University, Keller said.

In the late 1980s, when Fairfax Hospital was planning to construct a new building, Dr. Ziai knew the pediatric department on its own stood little chance of obtaining space in what would be the state-of-the-art facility. So he proposed linking his department with the obstetrics and gynecology division to build a larger maternity-child institute.

“He saw the mothers’ role in health care as being pivotal,” Keller said. “If you want to influence the health of a child, you have to work with the mother. So it was a natural alliance between the two departments that serve children’s health.”

The combined departments — which grew to include neonatal and pediatric intensive-care units, 30 medical specialties and more than 180 beds — opened at the new building in 1992 and became known as the Fairfax Hospital for Children. The name later changed to Inova Children’s Hospital.

Dr. Ziai forged academic training partnerships with the University of Virginia, Virginia Commonwealth University and other institutions. He left in 2000 and spent two years as chairman of pediatrics at Suburban Hospital in Bethesda.

Mohsen Ziai was born in Torbat-e Heydarieh, Iran, on July 29, 1927. He was a 1948 magna cum laude graduate of Davis and Elkins College in West Virginia and a 1952 graduate of Johns Hopkins University medical school.

He was chief resident at Boston Children’s Hospital, where his mentor was the noted infectious disease specialist and immunologist Charles A. Janeway. Dr. Ziai completed a fellowship in infectious diseases at Boston City Hospital and a research fellowship in medicine at Harvard Medical School.

In Iran, he became head of the pediatrics department at a hospital in Shiraz and dean of the medical faculty at the University of Tehran. In the 1970s, at the charitable agency known as the Imperial Organization for Social Services, he helped organize a project to train people from rural areas in the basics of public health and sanitation.

Dr. Ziai, who became a U.S. citizen in 1995, was an honorary fellow of the American Academy of Pediatrics, and his memberships included the Cosmos Club. His professional honors included an award from the Johns Hopkins Medical and Surgical Association for international medical education.

Survivors include his wife of 54 years, Nahid Gharib Ziai of Great Falls; four daughters, Niloofar Ziai and Parinaz Bahadori, both of Great Falls, Fatemeh Ziai of New York City and Ameneh Ziai of London; two sisters; and 10 grandchildren.

Dr. Ziai wrote medical articles and textbooks. He also edited “The Joys of Pediatrics,” a 2005 book of humorous medical anecdotes published by the American Academy of Pediatrics. One story involved a 4-year-old whose concerned mother brought him to the doctor for a hearing checkup. The young patient revealed, “I always hear her, but sometimes I just don’t want to answer.”