Her credentials are impressive: Coast Guard reservist, trophy-winning distance runner, veteran of risky Ground Zero duty on the morning the World Trade Center collapsed. Yet even Adrienne Walsh has felt the sting of resentment from men who do not want women alongside them in the ranks of firefighters.

Last year, Walsh became the first woman assigned to one of New York's elite Fire Department rescue companies. Within five weeks, she transferred out -- stunned that the company members chose to ostracize her. A few weeks ago she again took the trailblazing step, this time getting a warm welcome as she joined a rescue company in a different borough.

The eight-year firefighting veteran is proud of her achievements, grateful to many male colleagues who have supported her, yet frustrated by the slow pace of change in a department and a profession in which -- because of attitudes and difficult physical tests -- women remain a tiny minority.

"You have to change the department from the top down," Walsh said. "You've got to show people you want them."

Nationwide, the status of women in firefighting mirrors Walsh's up-and-down experience: Depending on where one looks, there is ample cause for celebration or dismay among those who want gender barriers lowered.

Of an estimated 296,000 professional firefighters, about 6,500, less than 2.5 percent, are women. That is up from zero as of 1972, but "nowhere near the point where you lose your token status," said Terese Floren, director of Women in the Fire Service, based in Madison, Wis.

Firefighting forces are more than 10 percent female in several big cities; two of them, San Francisco and Minneapolis, also have women as fire chiefs. But in Boston and Philadelphia, barely 1 percent of the firefighters are female; New York has 29 women out of more than 11,000 firefighters, or less than 0.3 percent.

In many other cities, women who got hired have complained of gender-related bias and harassment. Among the recent cases:

* A federal court is weighing whether to uphold awards totaling $335,000 to two women who contended they were discriminated against as firefighters in Kansas City, Mo. They said they faced retaliation for complaining that they were not provided proper protective gear and bathroom facilities.

* Two Bridgeport, Conn., firefighters recently lost a federal court suit seeking nearly $1 million in damages for alleged bias and harassment. The women said they were called vulgar names, given punitive assignments and exposed to pornography.

* Two women dismissed from a fire academy in St. Paul, Minn., received $100,000 each in a settlement of a discrimination suit. They said instructors forced them to take tests with broken equipment and refused to give guidance provided to other recruits.

* In Los Angeles, a dozen firefighters were disciplined recently for harassment of women and blacks in the department, which has 92 women in a force of 3,382.

"Firefighting is the last big macho stronghold," said Maureen McFadden of Legal Momentum, an advocacy group monitoring the bias cases. "As a society, we keep holding steadily to the notion of the brawny, mustachioed firefighter, even though physicality is less important to the job than it used to be."

No major fire department embodies a new approach to gender more than San Francisco's, in which 230 of the 1,700 firefighters are women, and the chief -- since January 2004 -- is Joanne Hayes-White, 41.

"The fire service is very rich in tradition, and I embrace that, but only to the point where it doesn't get in the way of moving toward the future," Hayes-White said. "The departments that, for whatever reason, have not embraced diversity -- I just feel they're missing out."

Some harassment still occurs, but more rarely than in past decades, the chief said. "We make a big deal out of it -- we discipline swiftly and appropriately," she said.

Among the slow-to-change areas is New Jersey; the last official count in 2002 showed 19 women among nearly 6,000 career firefighters. Even now, after modification of the state's physical exam and breakthroughs at several previously all-male departments, female firefighters there are believed to be fewer than 30.

But attitudes are changing. In Elizabeth, N.J., for example, a new firehouse is being built with a women's bathroom and locker room, even though the 262-member force is all-male.

"It will be a big cultural change from the way we normally operate, but we'd adjust fairly well," Department Chief Edward Sisk said. "It's only a matter of time."

A few miles away, Audra Carter and Maria Diaz have been low-key trailblazers since being hired -- to their surprise -- in December 2002 as the first female firefighters not only in their home town of Hoboken, N.J., but in all of Hudson County, which has 600,000 residents.

Now comfortable on the job, they laugh at how their arrival was preceded by sensitivity training for their 120 male colleagues.

"When we first came on, it was a little bit awkward -- the guys were walking on eggshells," told not to curse or do anything remotely like flirting, said Diaz, 31.

"But after six months, they were like, 'Hey, the girls are just like us,' " she said. "They curse as much as before we came on."

Carter, 33, said some of the men engage in "harmless teasing," while a handful still treat the women coldly. "You just keep your distance," she said.

Both women are 5-4 and trim, handling rigorous duties alongside far bigger men. They work out regularly to maintain the strength needed to pass the physical exam, in which they have to carry a 50-pound load up the equivalent of 12 flights of stairs while wearing a 40-pound fire vest.

"I just don't want to lag behind," Diaz said. "We had to get the guys confident that, when we go on a call, they can count on us."

Adrienne Walsh was sure that the men of Rescue 4, in Queens, could count on her. She had distinguished herself in an array of assignments since joining the New York City Fire Department in 1997, had won several fitness awards, and was well-received by most male colleagues.

Yet from the moment she arrived at the elite Queens company last year, the men there froze her out; one called her at home to convey a message of unwelcome. After 32 days, she requested a transfer -- though the story broke in the local media only because a male officer spread the news.

Walsh, 38, returned to her former company in Manhattan, then switched to Rescue 5 on Staten Island at the end of March.

"I worked very hard to learn and to get as far as I could in my career, and they were going to shut me out," she said of her experience in Queens. "When you ostracize someone, you can allow yourself to not like them and yet not know anything about them. . . . It was a jolt."

Walsh and her female colleagues have been urging the department to equip more firehouses with women's bathrooms and to recruit more women.

With a firefighting force that is 92 percent white male, the department is also under pressure to diversify racially. The U.S. Justice Department is investigating whether the testing process is biased.

Mike Marshall, vice president of a black firefighters society, said that his group has common cause with women in believing that Mayor Michael R. Bloomberg and other officials could do more to remake the fire department.

"They'll do the easiest things, not the drastic things," Marshall said. "If you had a mayor who said, 'I don't care what anyone thinks. I'm going to change the complexion of the department,' it would happen."

Audra Carter, left, and Maria Diaz have been trailblazers since being hired -- to their surprise -- in 2002 as the first female firefighters not only in their home town of Hoboken, N.J., but in all of Hudson County.