Thomas Thomsen, 86, a Veterans Administration lawyer who was active in community organizations in Northern Virginia, died Saturday at the Fairfax nursing center. He had cancer.

He joined the V.A. in 1945 and worked in field ofices in Lincoln, Neb., and the Philippines before coming to Washington in 1949. He retired in 1962.

Mr. Thomsen had been chairman of the Fairfax County Commission on Aging and had served as president of three different Northern Virginia garden clubs. He was a member of the Greenway Downs Citizens Association and received its outstanding citizen's award in the late 1960s.

He was a Mason for more than 50 years and was a member of American Legion Post No. 130 in Falls Church. He was a member of the Bethel United Church of Christ in Arlington.

He was a state director for the American Association of Retired Persons Washington Metropolitan Area chapter.

Mr. Thomsen was a native of Mitchell, S.D. He was a 1921 graduate of the University of Iowa and earned a law degree there six years later.

He served with the Army in France during World War I and received the Purple Heart Medal after being wounded during the Meuse-Argonne campaign.

Mr. Thomsen taught social studies at Grand View College in Des Moines, during the early 1920s, practiced law in Iowa from 1927 to 1939, then operated credit bureaus in Nebraska for about nine years before joining the Veterans Administration.

He is survivied by his wife, Frances, of the home in Fairfax; a daughter, Esther DeRaad, of Falls Church; one grandchild, and one great-grandchild.