Suddenly, everything isn't so rosy for Rosie Ruiz. Eight days ago, she was declared winner of the women's section of the 84th Boston marathon.

Today, she was stripped of her title. In between, she was accused of perpetrating one of the greatest hoaxes in sports history.

At a press conference this afternoon at the Prudential Building, Will Cloney, the race director, announced that, in a unanimous vote taken Monday night, the board of governors of the Boston Athletic Association (BAA) had declared Jacqueline Gareau of Montreal the 1980 women's champion.

Cloney told a news conference that a week-long investigation showed "beyond a reasonable doubt" that Ruiz did not cover all 26 miles 385 yards of the race.

But Ruiz said tonight in New York City that she would not give back her gold metal "because I believe it is for the honor of winning the big one, Boston, and honor I rightfully deserve."

"As for the proof of what I did, it will come on the streets of New York City when I show to all the people that I am a world-class runner."

Ruiz said she will run July 5 in the Diet Pepsi Regional 10K, which begins on the New Jersey side of the George Washington Bridge and ends in New York City. That race is being organized by the Suburban Road Runners Club, which is directed by Steve Marek. He has become Ruiz's advisor since the controversy began in Boston.

Cloney said official ceremonies would take place "in two weeks or so," when the men's winner, Bill Rodgers, returns from a publicity trip hyping his book on the marathon.

In the meantime, Cloney said, "I will assume the prerogative of (Boston) Mayor (Kenneth) White and put this crown on her head."

He then gently placed the traditional laurel wreath signifying victory in the country's oldest foot race on Gareau's head.

Gareau, who looked more withered than the wreath, raised her fist tentatively, and belately, in victory. She then reached up to touch the wreath, as if to make sure it finally was there.

"I think," she said, looking up under her eyebrows, "I will keep that in my home."

Asked if she might bronze the wreath to ensure that victory does not elude her again, she smiled and said, "Maybe. Maybe I will do just that."

It has been an agonizing week for Gareau, who was flown to Boston Thursday by local TV station WBZ "under false pretenses," Cloney said, that a decision was imminent.

Cloney said, "Our information was persuasive by last Thursday night, but we delayed our announcement until we could get a final report from the official race photographers. More than 10,000 photographs, taken with four-speed cameras at a point approximately a mile from the finish, were examined.

"Miss Gareau is shown clearly as the first woman runner. Miss Rosie Ruiz does not appear in the photo sequence; her number does not appear on any of our check lists."

Cloney said the BAA had been able to chart the women's race from the midway point to beyond Kenmore Square, one-half mile from the finish, using information from official checkers and from members of the media who had been assigned to cover the women.

The information "has enabled us to reach the conclusion beyond any reasonable doubt that Miss Jacqueline Gareau was the leading woman runner for the last 10 miles," Cloney said.

Although race officials did not chart the progress of the top women at key checkpoints (they charted only the top 100 men), radio volunteers at those checkpoints, who were responsible for relaying the information about the top men to the press center, also relayed information about the top women.

Cloney said that disqualification of Ruiz from last year's New York marathon, which had provided her qualifying time (2:56.29) for Boston, was not a factor in the decision.

Cloney met with Ruiz Monday night in Boston, and though he did not apprise her of what the decision would be, he said today, "I'm sure she knew.

"She didn't argue with our information and she didn't contradict it," Cloney said. "I said, 'Rosie, can you tell me anything that will contradict this information? She produced one man who said he saw her running with a man wearing No. 2981."

But No. 2981, Cloney said, was the 10th-place male finisher and could not have run with Ruiz.

"About 3 percent of our information supports Rosie," he said, "and we have not been able to corroborate much of it."

Cloney said that after talking with Ruiz for an hour, "I am convinced she thinks she ran the race and won the race and she is equally convinced, and this is a little strange, that our information is overwhelming.

"I know people want me to say that she came up here with the intention of doing this," he added later. "But I don't believe that it was intentional and that if she did anything it was spur of the moment. By this time, she's convinced herself that she did it. I'm not a doctor, not a psychiatrist or a psychologist, I wouldn't presume to figure it out."

Ruiz's medical history includes two brain operations, but the doctor who performed them has said they were successful.

Cloney said he had invited Ruiz to run in the 1981 Boston marathon, without a qualifying time, in order to give her a chance to vindicate herself.

Gareau, who will run in the Midlands 15-kilometer Sunday in Far Hills, N.J., was asked if she expects to see Ruiz at another race.

"Maybe she will come again with Mr. Marek," she replied. "I think now she is not a runner because the situation seems she didn't run. She is not a real runner and so she cannot run."

Gareau says she prefers "running to being interviewed," especially in English, which is not her native tongue.

"People were calling at 2 in the morning every night," said Serge Arsenault, her friend and adviser. "The worst part is not being able to train."

Gareau's time in Boston, 2:34.26, is a course record, and the fourth fastest time recored in a marathon by a woman. Gareau, a technician at a Montreal hospital, who has been competing for just two years, does not intend to try for the 1980 summer Olympics "because," she said, "I didn't work enough now on my speed to go there." The 1,500 meters is the longest Olympic run for women.

Gareau was third in the 1979 New York marathon. Asked if she would allow herself finally a sip of victory champagne, or at least a beer, she said, "I think I don't need that to celebrate."

Her face was shining, and it wasn't just from the television lights.

Cloney was hoping for a turkish bath and a home-cooked meal. The beleaguered but good-humored race director, who has overseen the race for the last 34 years, has been criticized by other race directors as being outdated. Time has passed Boston by, they say.

"I'm demonstrably incapable of doing the job I've been doing since 1946," he said, smiling and obviously meaning the opposite. "I don't think we should be in the position of defending the marathon anymore than Rosie Ruiz should be in a position of defending herself."

Cloney said he intends to have official checkers for the top five women at each checkpoint next year. But he scoffed at the need for videotape equipment, different colored numbers for women or a separate race for non-elite runners, as some race directors have suggested.

"That's easy for them to say," Cloney said. "All they know about marathoning they learned from Boston."