Ellen Hall Hornthal, 73, who was active in service organizations and medical societies, died Friday of a brain tumor at Oak Meadow Nursing Home in Alexandria.

Mrs. Hornthal was born in Fargo, N.D. She came here in 1924 when her father, Thomas Hall, then the Republican secretary of state for North Dakota, was elected to Congress, where he served until 1933.

She graduated from the old Colonial School for Girls and the old Fairmont Junior College and attended George Washington University.

In 1933, she married Dr. Henry Amiss Hornthal, who began practicing medicine here and in Alexandria in 1924.

She and her husband lived at the Fairfax Hotel here, where he maintained an office, until 1977, when they moved to Alexandria.

Mrs. Hornthal was a founder and past president of the Alexandria Medical Society women's auxiliary and a past president of the women's auxiliaries of the D.C. Medical Society and the Southern Medical Association.

She was a former member of the George Washington University Women's Baord. She also was active in the Congressional Club and the Washington Club and attended Metropolitan Memorial United Methodist Church here.

Besides her husband of the home in Alexandria, survivors include a daughter, Ann H. Merlo, of Elkin, N.C.; a brother, Richard G. Hall, of Wheaton, Ill.; a sister, Edna Rumreich, of Glen Rock, N.J., and two grandsons.

The family suggests that expressions of sympathy be in the form of contributions to Metropolitan United Methodist Church in Washington.