Marjory Hendricks, 81, founder of the Normandy Farm restaurant in Potomac, and of the old Water Gate Inn, which was torn down to make way for the Kennedy Center, died Monday in the Carriage Hill nursing home in Silver Spring. She had suffered from arteriosclerosis.

Mrs. Hendricks's restaurants were among the most popular in the Washington area. Normandy Farm, which she founded in 1931 and sold in 1958, was French, and still exists. The 'Water Gate Inn was Pennsylvania Dutch in decor and cuisine. Mrs. Hendricks opened it in 1941. It was taken by condemnation in 1966 for a reported $650,000, and closed with a party for its friends and patrons.

For some time in the 1960s, Mrs. Hendricks also owned the Renaissance Gift Shop on Massachusetts Avenue NW. In recent years, she had lived in rethement in Potomac and then at Carriage Hill.

During World War II, Mrs. Hendricks served in the military welfare service of the American Red Cross in Australia, New Zealand and Italy. She helped to establish and operate enlisted men's clubs in those countries.

In addition to her restaurant activities, for which she won a number of industry awards, she supported the American Heart Association, to which she gave the proceeds of an annual Valentine's Day party at the Water Gate Inn, and the Casa Materna, an orphanage operated by the United Methodist Church in Italy.

Mrs. Hendricks was born in Seattle, Wash. She grew up in Butte, Mont., Chicago, and Madison, Wis., where she graduated from the University of Wisconsin. Her family moved to the Washington area in 1918.

After attending graduate school at Bryn Mawr College. Mrs. Hendricks married Robert Davis in 1923. They were divorced in Reno, Nev., in 1927, and it was in Reno that Mrs. Hendricks opened her first restaurant. It was called The Corner Cupboard. She returned to Washington in 1928, then spent the next two years in France studying French cooking. She opened Normandy Farm after her return here.

That restaurant was closed during world War II, but the Water Gate Inn remained open. The Water Gate was noted for its hobby horses, which were among its decorations, as well as for its food.

Mrs. Hendricks resumed her maiden name after a second marriage ended in divorce.

Her survivors include a son, Roger Todd Davis, of Pullman, Wash., and a niece, Mrs. Sherman Littlepage, of Washington.