Dr. Leonard W. Cronkhite Jr., who served as president of Children's Hospital for 15 years, died Saturday at his home in Maine. He was 77.

Children's Hospital is one of more than half a dozen Harvard-affiliated teaching hospitals. In addition to his service at Children's Hospital, Cronkhite was a lecturer in preventive medicine at Harvard Medical School and Massachusetts General Hospital.

Cronkhite ascended to the Children's Hospital presidency in 1962. During his term, he significantly expanded the hospital, adding an ambulatory care center and an adjacent Inn at Children's for patients undergoing diagnostic testing and families of long-term patients.

Cronkhite was able to foresee the role that technology would come to play in medical administration. He developed and implemented at Children's the nation's first computerized system for scheduling outpatient visits by appointment, putting an end to the traditionally long waits in clinics.

Cronkhite was also a savvy fundraiser. Even in an era when federal spending was tight, he managed to convince the government to fund the construction of the John F. Enders Pediatric Research Laboratories, which helped Children's Hospital become the largest pediatric research center in the world and the fourth largest research institution in the country.

"Len dedicated his career to improving the health and well-being of children the world over through his unique abilities as a physician, educator and administrator," said David S. Weiner, the current president and chief executive officer of Children's Hospital who succeeded Cronkhite as president. "At Children's, he brought extraordinary leadership and a vision of the changing role of the modern hospital in our complex society."

Cronkhite was born in Newton, Mass. in 1919, and was educated in Needham public schools and Bowdoin College.

After seven years of military service, he returned to Bowdoin to complete his bachelor's degree, and subsequently proceeded to Harvard Medical School, where he earned his M.D. in 1950.

Cronkhite's stepmother was the late Bernice Brown Cronkhite, a former dean of Radcliffe College and dean of Radcliffe Graduate School for whom the Cronkhite Center is named.

Dr. Cronkhite is survived by his second wife, Linda Marchky Cronkhite, and four daughters from his first marriage