Janet Bryant Riddle, 61, a retired economist with the Department of Commerce, died Jan. 31 at her home in Falls Church of injuries suffered in a fall.

She had joined the Office of Business Economics, now the Bureau of Economic Analysis, at Commerce in 1960s, and retired in February, 1975. During her tenure there, she had played an important role in the development of input-output tables of the U.S. economy.

Born in Le Roy, N.Y., Mrs Riddle graduated from Mt, Holyoke College in 1963, when she came to Washington. She worked for several federal government agencies before joining the Bureau of labor Statistics in 1949.

From 1954 until 1960, she was with the Central Intelligence Agency.

Mrs. Riddle was a charter member in 1951 of the Falls Church League of Women Voters and belonged to the Falls Church Citizens for a Better City.

Since retiring, she had been a active in the Mt. Holyoke College Alumnae Association and had served as a volunteer in the library of the Timber Lane School in Falls Church.

She is survived by her mother, Janet Olson Bryant, of Le Roy, and a brother, Donald B. Bryant of Lakewood, Ohio.

The family suggests that expressions of sympathy may be in the form of contributions to the Mt. Holyoke College Scholarship Fund, South Hadley, Mass.