Muriel Milton Alexander, 80, a retired D.C. public school principal and a member of the first school board to be elected here in this century, died Sunday at Howard University Hospital.

Mrs. Alexander won her seat on the board from the Fourth Ward in a runoff election in November, 1968. She received a three-year term and did not seek re-election.

In 1967, she had retired as principal of Kelly Miller Junior High School. She had been named the school's first principal when it open in 1949.

Born in Washington, Mrs. Alexander graduated from the old M Street High School and Miner Normal School in 1916, when she started work in the public schools here.

She later received a bachelor's degree from Howard University and a master's degree from New York University of California at Los Angeles and the Sorbonne in Paris.

Mrs. Alexander was a teacher, then a counselor, and assistant principal at Banneker an d Browne junior high schools before she became principal of Kelly-Miller.

When she ran of election to the school board, she emphasized her many years of experience in the school system. She called then for reduction in class size and a stepped-up reading program.

Considered a moderate on the board, she also favored community participation in the decision-making process of the schools but was opposed to outright community control. She supported giving teachers a greater voice in selecting the curriculum.

Mrs. Alexander had been active in many civic and educational organizations. She was a founder and director of the Washington Urban League.

She was a member of the American Association of University Women, the National Association of College Women, the National Association of Secondary School Principals, the National Council of Negro Women and the Business and Professional Women's Club.

Mrs. Alexander, who lived in Washington, had been active in the Phyllis Wheatley YWCA and the Howard University Women's Club. She was a former superintendent of the Sunday school of the Third Baptist Church.

She is survived by three brothers, Lorimer D. Milton, of Atlanta; Dr. Samuel B. Milton, of Lincoln Par, k, Mich., and Dr. Boynton A. Milton, of Inkster, Mich.