Worth Bagley Daniels, 79, a specialist in internal medicine in Washington for 48 years, died Tuesday at his home in Washington of pneumonia.

Dr. Daniels, who was born in Raleigh, N.C., went to St. Albans School in Washington. He graduated from the University of North Carolina in 1920, and from the Johns Hopkins University School of Medicine in 1924.

He set up his medical practice in Washington in 1926 and was on the staff of Georgetown Hospital and the Washington Hosptial was supporting the Needy Sick Fund at the Washington Hospital Center. He retired in 1974.

In addition to his medical practice, Dr. Daniels was a professor of clinical medicine at Georgetwon University, and in 1962 received an honorary doctor of science fromthat institution.

He was the first chairman of the Board of Regents of the National Medical Library in Bethesda and was a master of the American College of Physicians. He also was a member of the Association of American Clinical and Climatological Association, the Clinical pathological Society, the Alibi Club, the Alfafa Club, and was a turustee of the Johns Hopkins University.

During World War II, he was in the Army medical Corps and for a short time in 1946 was chief of medicine at Walter Reed Army Medical Centre.

He wrote on meningococcus infections and on cat-scratch fever for the armed forces during the war.

Survivors include his wife, Josephine J., of the home in Washington; two sons, Worth B. Jr., of Baltimore and Derick J., of Chicago, the president of Playboy Enterprises Inc., which publisheds Playboy Magazine, and four grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Needy Sick Fund, Washington Hospital Centre, Washington, D.C.