Florence Mathews Feighan, 78, an advocate of American Indian rights and a Washington resident since 1943 when her husband, Michael A. Feighan, came here as a freshman Democratic congressman from Ohio, died of cancer Wednesday at Greorgetown University Hospital.

During her husband's 28 years in Congress, Mrs. Feighan became a familiar Washington figure. She organized her own Capitol Hill home tours for disabled servicemen and their families and was active in the Congressional Club, where she served on the advisory board. She served as president of the 78th Congress Club, whose members included congressmen who served their first term in the 78th Congress, and their wives, and also was active in the Woman's National Democratic Club.

Born and reared in Pawhuska, Okla., near the Osage Indian Nation, Mrs. Feighan was the great-granddaughter of an explorer and frontiersman and the daughter of an Osage tribal chiefan. She was educated by private tutors and graduated from St. Mary-of-the-Woods College in Indiana.

While a student there, she helped found the Children of Mary Sodality and later served as its national president. She also was a founding member of the National Council of Catholic Women.

Mrs. Feighan and her husband also maintained homes in Cleveland and Scottsdale, Ariz. She was active in the Congressional Country Club in Bethesda and the City Tavern club.

She and her husband were married for 49 years.

Besides her husband, survivors include a daughter, Fleur Jones of Bronxville, N.Y.; a son, William M., of Washington and Scottsdale; two sisters, Marie and Lillian Mathews, both of Pawhuska, and a grandson.

The family suggests that expressions of sympathy be in the form of contributions to the Florence Mathews Feighan Scholarship Fund.