STAMFORD, Conn. — Polly Lauder Tunney, the Carnegie Steel Co. heiress whose marriage to heavyweight boxing champion Gene Tunney made international headlines in 1928, has died, her family said. She was 100.

Tunney, whose husband died in 1978 at age 81, died Saturday at her home in Stamford, a son, Jonathan R. "Jay" Tunney, said today. One of her other sons is former Sen. John V. Tunney of California.

Mary "Polly" Lauder was 21 when she married Tunney in Italy in 1928, a year after he successfully defended his heavyweight boxing title against Jack Dempsey in the famous "long count" fight in Chicago.

According to a biography published last year, he promised his fiancee he would quit boxing and defended his title just once more, with a TKO of New Zealander Tom Heeney.

The engagement of Tunney, who escaped a childhood of poverty through his boxing prowess, and his heiress sweetheart was the source of much speculation and media attention.

The Los Angeles Times headlined one story "WEDDING GONG CALLS GENE, This Time Heiress to Steel Millions Rumored as Ready to Sign Up With Champion." A later story datelined Rome had as a subhead: "Bride-to-be Quickly Hidden in Hotel as Eternal City Burns With Curiosity."

The New York Times reported that after the wedding, photographers had their clothes torn and cameras smashed in "something that looked mighty like a riot" as they tried to capture the couple leaving the ceremony.

Polly Tunney's grandfather was George Lauder, first cousin and close business partner of industrialist and philanthropist Andrew Carnegie, founder and head of Carnegie Steel Co.

Her father, George Jr., was a philanthropist and yachtsman whose 136-foot schooner once held the record for the fastest trans-Atlantic yacht passage ever made, Jay Tunney said.

John Tunney, born in 1934, was a three-term congressman when he was elected to the Senate from California in 1970, defeating incumbent Republican George Murphy, a former Hollywood song and dance man. He served one term before he was defeated in 1976 by Republican S.I. Hayakawa.

Other survivors include another son, Gene L. Tunney of Honolulu, and a daughter, Joan Cook of Arkansas.

Their late father is most famous in boxing annals for the fight with Dempsey on Sept. 22, 1927, in front of 104,000 at Soldier Field in Chicago, a rematch of a bout won by challenger Tunney in an upset a year earlier.

Dempsey knocked Tunney to the canvas in the seventh round, but the referee delayed the count because Dempsey did not immediately heed a new rule that it could not start until the fighter was in a neutral corner. Tunney rose at the count of nine and went on to win the match. Many fight fans and reporters contended that Tunney would have been counted out if it had not been for the delayed count.