Leila Pier King, 99, the author of a book on poetry whose work as included in a 1970 anthology of American poems, died Friday at the Bethesda Retirement and Nursing Center in Chevy Chase. She had arteriosclerosis.

Mrs. King was the author of a book of poems written over a 30-year period, "The Hunter's Horn," published in 1950. Two of these poems, "We Walk with Lincoln" and "Tomb of the Unknown Soldier," were included in a 1970 Harper & Row anthology, "Our American Heritage."

Born in the Dakota Territory in 1882, Mrs. King was married in 1902 to W.H. King, who later became an official of the Agriculture Department. She and her husband moved to Washington in 1927 and to Silver Spring in 1934. He died in 1964.

In 1975, Mrs. King went to live with her son, retired Army Col. Harrison King of Washington. The following year, she moved to the retirement center.

Mrs. King was a past national chaplain of the League of American Penwomen, a 60-year member of the P.E.O. Sisterhood, a philanthropic educational organization, and a member of the Silver Spring Woman's Club.

Besides her son, survivors include a daughter, Theodora King Neil of Des Moines, Iowa; a brother, Leonard A. Pier of Rapid City, S.D.; five grandchildren, and five great-grandchildren.