Constance Marcy McGregor, 67, a former Senate aide and CIA employe who was active in service and church organizations, died Tuesday at the Franklin Regional Hospital in Franklin, N.H., after a heart attack. She lived in Washington and maintained a summer residence in West Franklin, N.H.

Mrs. McGregor, who was born in Newton, Mass., attended Vassar College and graduated from Wheaton College in Norton, Mass. She married Robert G. McGregor, a Foreign Service officer, and accompanied him on an assignment to Mexico. She later returned to Newton.

In 1948, her marriage having ended in divorce, Mrs. McGregor moved to Washington and joined the staff of Sen. Leverett Saltonstall (R-Mass.) She worked there for about five years and then joined the CIA.

About 1955, she resigned from the agency and married William H. Lawrence, a former correspondent for The New York Times and national affairs adviser for the American Broadcasting Company. When that marriage ended in divorce, she resumed the McGregor name.

Mrs. McGregor was active in fund-raising drives for the American Red Cross and the March of Dimes. She also was a volunteer with Hospice Care of D.C. She was a member of All Souls Unitarian Church and for many years arranged the flowers on the altar.

Survivors include two daughters by her first marriage, Susan McGregor of Washington and Judith Caldwell of Darien, Conn.; a brother, Richard C. Marcy of Marblehead, Mass.; Jeanne M. Berwind of Boston, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to Hospice Care of D.C., 1749 St. Matthews Court, N.W., Washington, D.C., 20036,