Mildred Parker Merrell, 73, a former member of the Northern Virginia Planning and Economic Development Commission, died of cancer Monday at her home in McLean.

Mrs. Merrell was born in Columbus, Ohio, and attended Ohio State University before moving to Fairfax County in the 1920s. She was the widow of Douglass S. Mackall Jr., of Charles Pickett, and of Charles Merrell.

In addition to her service on the planning commission, Mrs. Merrell was a member of the board of the Northern Virginia branch of the Children's Home Society of Virginia. Garden Club of Fairfax and a secretary of the Young Democratic Club of Fairfax County.

Mrs. Merrell was a member of the Daughters of the American Revolution, the Colonial Dames, the Jamestown Society, the Mayflower Society, the Daughters of the Cincinnati, the City Tavern Club and the Army & Navy Club in Washington.

She was a member of St. John's Episcopal Church in McLean.

Survivors include two sons, Henry C. Mackall, of McLean, and Douglass S. Mackall III, of Fairfax; a stepson, the Rev. Charles Pickett, of Washington; two stepdaughters. Beverley Pickett Kirchmier, of Chesapeake, Va., and Julia Merrell Tucker, of McLean; a sister, Florence Hohenstein, of Washington; a brother, Richard LeRoy Parker, of Arlington, and five grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Fairfax County chapter of the American Red Cross.