Phyllis Ann Thomas, 51, a nurse at the Walter Reed Army Medical Center and a resident of the Washington area most of her life, died Saturday at Walter Reed following surgery for cancer.

Mrs. Thomas was born in Washington, graduated from Holy Cross Academy and earned her nursing degree from Georgetown University. She was a nurse at Georgetown in the early 1950s.

Following her marriage to Joseph A. Thomas, now a retired Army first sergeant, she lived in France, Italy and at various military posts in the United States. But most of her husband's military career was in the Washington area and the couple had maintained a home here since 1953.

A resident of Riverdale at the time of her death, Mrs. Thomas had been a volunteer school nurse at St. Bernard's School in Riverdale. She resumed nursing full-time about 18 months ago, when she joined the staff of Walter Reed.

Mrs. Thomas was a member of the parish of St. Bernard's Catholic Church in Riverdale and of its Sodality.

In addition to her husband of Riverdale, survivors include two daughters, Kathleen A. and Bernadette L., also of Riverdale; four sons, Matthew A., of Ventura, Calif., John A., of Laurel, and Mark A. and Patrick I., both of Riverdale; her mother, Mary Gillespie, of Orlando, Fla.; a brother, John E. Turton, of New Orleans, and two grandchilren. Another son, Michael A., died in 1974.

The family suggests that expressions of sympathy be in the form of contributions to the Michael A. Thomas Scholarship Fund, De Matha Catholic High School, Hyattsville, Md.