Donald N. Medearis Jr., who served from 1977 to 1995 as chief of pediatrics at Massachusetts General Hosptal (MGH) and Charles Wilder Professor of Pediatrics at the Medical School, died of heart failure at the hospital on Sept. 29. He was 70.

Medearis had been professor and co-chair of pediatrics at Case Western Reserve University in Cleveland and professor and chairman of pediatrics and later dean of the School of Medicine at the University of Pittsburgh. He was a native of Kansas City, Kan., and lived in Winthrop.

As MGH chief of pediatrics, Medearis expanded and enriched an already flourishing department, and was instrumental in establishing an integrated Medicine/Pediatrics residency training program at MGH and Brigham and Women's Hospital, the founding members of Partners HealthCare System. He was also active in numerous positions and committees at the Medical School. From 1991 to 1993, Medearis chaired a nationwide, 19-member committee of experts appointed by the Institute of Medicine of the National Academy of Sciences to evaluate emergency services for children. He also was appointed by President Jimmy Carter to serve on the President's Commission for the Study of Ethical Problems in Medicine and Behavioral Research from 1979 to 1982.