William D. Dolan Jr., 86, who served as chief of pathology at Arlington Hospital for nearly 50 years before retiring in 1995, died of congestive heart failure June 4 at his home in Arlington.

Dr. Dolan joined Arlington Hospital in 1947 and was credited with transforming the community-based laboratory into a sound department of clinical pathology.

He was an assistant medical examiner in Arlington County in the 1950s and pioneered the county's cancer detection plan. In later years, he served as president of Arlington Hospital medical staff and was a member of the hospital's board of trustees and board of directors.

He also helped create the American Society of Clinical Pathologists Education Center in Chicago, the first center for year-round continuing education of clinical laboratory personnel, and the establishment of a teaching affiliation between Arlington Hospital and Georgetown University medical school, his alma mater.

Dr. Dolan took part in scientific studies and helped establish the American Blood Commission, which looked into the development of a national system for producing an adequate and safe supply of blood for medical use. He served as the commission's president in the early 1980s.

He held leadership posts in the Council on Scientific Affairs of the American Medical Association, the ASCP and the American Society of Clinical Pathologists.

Dr. Dolan was an assistant dean and clinical professor of pathology at Georgetown University and chairman of the board of Marymount College.

Dr. Dolan was a native of Westerly, R.I., and a graduate of the University of Rhode Island. He served his internship and a residency at Georgetown University Hospital before entering the Army in 1944. Serving in France, he tended to the wounded at Omaha Beach.

Additional assignments took him to Italy, Austria and finally Nuremberg, where he assisted in assembling the pathological data for the war trials.

He was a member of St. Agnes Catholic Church in Arlington and Washington Golf and Country Club.

Survivors include his wife of 57 years, Christine S. Dolan of Arlington; two sons, William III, of Arlington, and John P., of Bethesda; a daughter, Mary Anne Dolan of Los Angeles; a brother; and two grandchildren.