Margaret Russo, 56, a professional tennis player who won more than 25 national senior tournaments, died Oct. 11 of brain cancer at her home in Vienna. She also worked at the World Bank for 33 years.

Before she came to the Washington area in 1970, Mrs. Russo had been the eighth-ranked junior (under 18) tennis player in her native Australia. She began her career at the World Bank as a secretary in 1970 and continued to play tennis as she raised her family.

In 1973, she and her husband, Eugene Russo, also a tennis player from Australia, went on the professional tennis tour in Europe.

Later that year, Mrs. Russo resumed her career at the World Bank as a benefits counselor. After holding several other positions, she was named manager of appointments in the human resources department in 1998. She retired because of her illness in 2004.

From the early 1970s until 2004, Mrs. Russo won more than 100 singles and doubles tennis championships in the mid-Atlantic section of tournaments sponsored by the United States Tennis Association.

She won more than 25 national senior tennis championships in singles and doubles competitions. She won her first national singles championship in 1983 in the 35-and-over age division. In her final national championship in 2004, Mrs. Russo won the singles and the doubles titles in the 55-and-above division. She won national titles on three surfaces: grass, clay and hard court. She was ranked No. 1 in the United States on several occasions and never was out of the top five.

Mrs. Russo represented the United States in international senior team competition four times. In 2003, when she was the playing captain of the over-50 and over-55 teams, her teams won the two competitions, held in Germany and Turkey. Mrs. Russo did not lose a match in either tournament. She was the first American to win in two age divisions in the same year. In 2004, she was named an honorary member of the 55-and-over team.

In 1998, Mrs. Russo and her husband were inducted into the United States Tennis Association/Mid-Atlantic Tennis Association's hall of fame. She continued to play tennis, even after her initial cancer diagnosis.

In 1995, after she became a member of Westwood Country Club in Vienna, Mrs. Russo became a golfer. She lowered her handicap to 12 and participated in club tournaments locally and throughout the state.

She was co-captain of Westwood's Career Women's Golf team and continued to play golf until a few months before her death.

Mrs. Russo was born in Adelaide, Australia. She began playing tennis as a girl and met her husband when both were teenage players. They were married in 1969 and became U.S. citizens this summer.

As partners, the Russos won 17 mixed-doubles tennis tournaments and never lost a match when they played together.

Mrs. Russo was a member of Our Lady of Good Counsel Catholic Church in Vienna.

In addition to her husband, of Vienna, survivors include two children, Derek Russo of Boulder, Colo., and Alicia Birnie of Teton Valley, Idaho; her mother, Helen Dunn of Adelaide; two sisters; and one brother.

Margaret Russo continued to play tennis after her cancer diagnosis.