Julia (Judy) Lambis, 25, a 1974 graduate of Bethesda-Chevy Chase High School who had been a volunteer worker in health care programs, died Friday at Holy Cross Hospital in Silver Spring. She had Beta-thalasemia major, or Cooley's anemia.

When she was a year old, Miss Lambis was diagnosed as having Cooley's anemia, a hereditary disease that manifests itself as an inability of the body to produce its own blood and that last year claimed the life of a brother, Nicholas, at the age of 27.

Like her brother, Miss Lambis was treated at the National Institutes of Health, where she had been a patient since 1966, and had participated in NIH experiments to advance treatment of the disease. Before the introduction of the drug Desferal in 1973, treatment consisted primarily of blood transfusions.

Until the development of Desferal, which lengthened life expectancy and enabled patients to continue blood transfusions without dangerous side effects, life expectancy for victims of the disorder was 13 to 17 years.

In addition to undergoing treatment for the disease, Miss Lambis had volunteered for video-taped interviews and posed for pictures to help scientists studying Cooley's anemia, according to officials at NIH.

Miss Lambis was born in Washington and lived in the city with her mother, Eugenia Lambis, at the time of her death. Other survivors include four sisters, Jenny Fytras of Brooklyn, N.Y., and Phyllis Axarlis, Angela Tatakis, and Barbara Lambis, all of Silver Spring, and two brothers, James of White Oak, Md., and Constantine of Falls Church.

The family suggests that expressions of sympathy be in the form of contributions to Saints Constantine and Helen Greek Orthodox Church in Washington.