Dorothy Estes Ellis, 70, active in Washington Cathedral organizations, died of cancer Monday at her home in Washington.

Born in Orlando, Fla., she had lived there most of her life until moving to Washington five years ago. Her husband, William Nicholson Ellis, an Orlando attorney, died about 15 years ago.

Mrs. Ellis had attended the National Cathedral School for Girls in Washington. She also had studied at State University and Rollins College in Florida.

She was an officer of the Alumni of National Cathedral School and vice chairman of the Washington Committee of the National Cathedral Association. She had helped establish the Cathedral Choral Society and served it as president.

Mrs. Ellis was a former director of the Florida House of Washington. She belonged to the National Press Club and the Junior League of Washington. She was a board member of the Washington Club and a committee member of Folger Shakespeare Library Acquisitions. She belonged to Christ Church in Georgetown.

She is survived by two daughters, Judith Foster, of Franklin, La., and Ramelle Harpe, of Columbus Air Base, Miss.; a sister, Elinor Miller, of Winter Park, Fla., and four grandchildren.

The family suggests that expressions of sympathy may be in the form of contributions to the Washington Cathedral.