Dr. Donald Dewald, founder of Ohio Cancer Specialists, was a native of Crestline, Ohio and graduated from Crestline High School, The College of Wooster, and Case Western University School of Medicine. He did his post graduate residency at Yale University Hospitals. He was board certified in Internal Medicine and served as Chief Medical Officer at Letterman General Hospital in San Francisco during World War II.

Dr. Dewald returned to Mansfield and opened his practice of internal medicine on December 1, 1946. His son, Donald L. Dewald, joined the practice in 1980.

Dr. Dewald enjoyed his practice and his patients and had continued to see patients, even up until his death in 2001.

He was married to his wife, Eleanore, for 58 years and they have two daughters and one son.