ODY, Wyo. - That Copenhagen Cowboy, as they called Kent Cooper, was a saddle bronc rider on the rodeo circuit, one of the best in the world at trying to keep his spurs high on a horse that wanted no part of him. When he died two years ago at 47, the throat cancer was so bad it wrapped around his jugular vein and got into his brain.

His name lives on, here in the place that calls itself the rodeo capital of the world and in every town where cowboys wrestle animals under starry skies. But Mr. Cooper's legacy may be something more unsettling than his many winning rides.

The Cooper family has sued the nation's leading maker of chewing tobacco, which is also the oldest sponsor of rodeo, charging that the company addicted Mr. Cooper to a cancer-causing product without adequate warning about its hazards. Smokeless tobacco, known as chew or spit, is the drug of choice on the bull and bronc circuit, given away at sampling tents, promoted through banners and college scholarships and by charismatic champions who tell people it is part of Western culture.

Mr. Cooper's ex-wife, Susan Smith, and a small but growing number of cowboys say smokeless tobacco has made tooth-stained addicts out of too many rodeo riders and has no place in a fast-growing sport that appeals to families.

"Kent was a billboard for tobacco," Ms. Smith said. "They all are. But I wish people knew about the other side of it. He was so addicted to it he couldn't get out of bed in the morning without putting a wad in his mouth."

At a time when cigarette use has fallen and tobacco's ties have been severed with most major sports - including, this year, the former Winston Cup of Nascar - rodeo is one of tobacco's last entertainment refuges. And smokeless tobacco, which delivers nicotine when placed between a user's lip and gum, is the only growing segment of the industry, gaining new users in rural America. Rodeo, watched by about 23 million people in North America last year, is the rare sport where many, if not most, athletes are regular users of tobacco, which is as routine as rawhide.

"I'll chew till my lip falls off," said Matt Burch, a 27-year-old Wyoming cowboy who owns a rodeo company and took up tobacco as a young boy. "It's part of the code of the West - let a guy do what he damn well wants to do."

Ms. Smith and her 9-year-year-old son, Will Cooper, are suing the U.S. Smokeless Tobacco Company, which makes Copenhagen and Skoal, the leading brands, each accounting for more than $1 billion in sales annually in the United States. The company is owned by UST Inc. of Greenwich, Conn. The suit was filed in April in federal court in southern Idaho, where Mr. Cooper lived.

Copenhagen sponsored Mr. Cooper and gave him free tobacco for much of his professional life. With prize money low until recently, and a can of tobacco costing nearly $5, sponsorship can make a big difference.

When his rodeo days were over in the mid-1990's and he was broke, Mr. Cooper sometimes bought tobacco instead of diapers, Ms. Smith said. She is seeking an unspecified amount of money from the tobacco company, but says she does not expect to win any. What she wants is to see chew driven out of rodeo.

In the suit, the family says that Copenhagen, with its high nicotine content, "is far more addictive than almost any other brand" and "has a high concentration of those components of spit tobacco that carry the greatest risk of causing cancer."

Company officials refused to comment on the lawsuit, but said the company had been a responsible sponsor of rodeo and had worked hard to keep the product away from young people. Copenhagen was introduced in 1822 and is one of the oldest trademarks in the United States.

"We are proud of our long history of supporting the sport," said Jon Schwartz, a spokesman for UST. "Our product is a legal product for adults only, and it's part of the Western way of life."

The company reached an agreement with 45 states in 1998, offering a range of advertising restrictions, foremost of which is that it no longer displays brand names at rodeos but instead has banners for U.S. Smokeless. Samples are still given away.

It would be hard to find a more iconic symbol of one kind of Western man than Kent Cooper. Raised as a Mormon in Idaho ranch country (the Mormon Church urges its members to refrain from tobacco, caffeine and alcohol), he took up smokeless tobacco at the age of 13, his friends said, because it was all around him.

Handsome, rough-hewn and charismatic, Mr. Cooper became one of rodeo's best-known riders in the saddle bronc competition, the signature event of the sport, where a cowboy gets points for staying on a kicking, wildly bucking horse. He qualified 13 times for the national rodeo finals.

"He would have won it all one year except he decided to go off and go hunting," said Tony Martoglio, a former rodeo cowboy in Cody.

Mr. Martoglio suffered from throat cancer himself, but he still chews tobacco. "It's the American way," he said of his decision not to give it up. "You've got the right to make your own choice."

Ms. Smith and Mr. Cooper were married for 11 years and had one child. Tobacco was always a part of Mr. Cooper's life.

"He tried to quit," Ms. Smith said. "But he needed it at all hours - first thing in the morning, all day, late at night. He was one of those who never spit. He swallowed it."

She said he was never sick until he developed throat cancer a few years ago. On the rodeo circuit, smokeless tobacco is part of a festive tableau, beginning at the college level. U.S. Smokeless has given out nearly $5 million in scholarships over the last 30 years to college rodeo participants, and it sponsors luncheons and other events.

The commissioner of the National Intercollegiate Rodeo Association, John Smith, said the college rodeo circuit valued the boost it got from smokeless tobacco.

"We all need the money," he said. "We're not hypocritical. We'd take beer money if we could get it."

He said only a handful of the colleges with rodeo programs did not allow tobacco sponsorship or banners.

The sponsorship money is bigger on the pro circuit. Standings are sponsored by Jack Daniel's, the whiskey maker. The sport's best-known athlete, Ty Murray, identified as a seven-time World Champion All Around Cowboy, appears in print advertisements saying, "My three priorities in life are my horse, my rope and my Copenhagen, but not necessarily in that order."

But there are new voices among the horses and bulls these days. A man who calls himself Cowboy Ted Hallisey has been setting up booths at rodeo grounds where he warns children of the dangers of smokeless tobacco. Mr. Hallisey says he is a former user of smokeless tobacco, a habit he says he picked up at age 15 at the rodeo. He exudes the passion of a reformed addict.

"The Kent Cooper case is going to blow the doors open on the relationship between this drug and this sport," said Mr. Hallisey, who lives in Kanab, Utah.

Officials at the Professional Rodeo Cowboy Association said they would re-examine their relationship with smokeless tobacco before signing any new deal when their 10-year contract ends next year.

"I don't know if today's rodeo is the same as it was 10 years ago," said Leslie King, a spokeswoman for the association. The riders have attracted other sponsors, including jeans companies and salsa makers.

People in the tobacco industry and many rodeo cowboys say chewing tobacco is safer than smoking it. But last year the surgeon general, Dr. Richard H. Carmona, said in Congressional testimony that it was a myth that smokeless was a safe alternative to cigarettes. Cans and pouches carry warning labels about gum disease and cancer.

Each year, 30,000 American are found to have oral cancer, and about 8,000 die of it.

But cowboys can feel immortal, particularly on summer nights in Cody, where there is a rodeo every night through the end of August.

"Cowboys are going to chew tobacco no matter what you tell them," said John Costello, a former rodeo athlete who announces events here. He chews as well.