Adelaide LeRoy Tuttle Morgan, 81, a well known hostess here for many years and a community activist, died of cardiac arrest Monday at her home in Chevy Chase Village.

A pianist and soprano, she had entertained at her home and at USO and Junior League benefits. She had lived in Chevy Chase Village for 56 years.

Her husband, Charles Carroll Morgan, an investment broker and president of Suburban Hospital and the Chevy Chase Club, died in 1970.

Mrs. Morgan had served on the boards of Suburban Hospital, the old Emergency Hospital and Washington Hospital Center. She had campaigned for the American Red Cross, the Community Chest and the National Symphony Orchestra.

She was born in Washington and attended the Potomac and Holton-Arms schools, which were within walking distance then of the family home on Connecticut Avenue. She graduated from Westover, a private school in Waterbury, Conn.

During World War II, Mrs. Morgan was a nurse's aide at Walter Reed Hospital.

She was a member of the Chevy Chase and Sulgrave clubs and All Saints Episcopal Church.

She is survived by a son, LeRoy Tuttle Morgan, of Clarksburg, Md.; a sister, Mrs. Streeter Blanton Flynn of Oklahoma City, and seven grandchildren. Another son, C. Carroll Morgan Jr., died in 1956.

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