Barbara A. Boyes, 49, assistant commissioner of the Labor Department's Bureau of Labor Statistics, died of cancer Friday at her home in Washington.

Miss Boyes came to Washington and began her government career as a mathematical statistician supervisor with the Census Bureau in 1957. She transferred to a similar position with the Bureau of Labor Statistics in 1972. Two years later she was promoted to assistant commissioner and head of the office of survey design, posts she held until her death.

She had been secretary of the American Statistical Association's section on survey research methodology in 1979 and 1980. She was a member of the International Statistical Institute, the International Association of Survey Statisticians, and the American Association of Public Opinion Research.

Miss Boyes was born in Indiana and was a 1957 graduate of the University of Minnesota where she earned a bachelor's degree in mathematics and statistics. She did graduate work at American University and the Agriculture Department's graduate school.

She was a member of the Davies Memorial Unitarian Church in Camp Springs.

Survivors include her mother, Margaret Boyes, and two sisters, Enid J. Torrell and Susan Braun, all of Minneapolis, and a brother, Federic R. Boyes of Mankato, Minn.

The family suggests that expressions of sympathy by in the form of contributions to George Washington University Hospital's Home Care Program.