Gay men and lesbians marched and danced and sang their way up Fifth Avenue today in a serious and saucy celebration of Gay Pride Day.

The city's top politicians marched alongside drag queens on floats, nearly naked dancers and men wearing sequined gowns, feathered boas and tight miniskirts.

Thousands of spectators cheered the spectacle through the heart of Manhattan on a hot, sunny afternoon.

The 28th annual march was used to launch an effort to help healthy people "stay free of HIV as we enter the 21st century."

"Got 2 B There" -- for the millennium -- said T-shirts calling on at least 2,000 volunteers to join an HIV-prevention program named "Beyond 2000."

"Gay men changed the face of public health by inventing a safer sex culture," said Richard Elovich of the Gay Men's Health Crisis, which is sponsoring the project.

On the West Coast, thousands of revelers turned out for San Francisco's annual gay pride parade down Market Street, led by several hundred women on motorcycles.

"I love it. I think it's great," said Nathaniel Downes of Santa Cruz, Calif. "It's kind of like saying, Hello, hello, we exist.' . . . {Even} people who don't want to be here still know it's going on. It's a matter of existence."

"We truly are every age, every race, every religious background, every economic and educational background. We're everyone's brother and son and sister and daughter," said San Francisco parade spokeswoman Denise Ratliff.

The New York marchers reserved some of their whistles and boos for Mayor Rudolph W. Giuliani (R), who has said he opposes legally sanctioned gay marriages. He responded with a broad smile but picked up his pace.

"I'm all for the mayor marching. But it's very hypocritical," said Lynn Ringhaver, a nurse who has cared for HIV-positive patients.

But most of those celebrating weren't there to watch politicians.

"I adore my lesbian daughters, keep them safe," said a sign held by 73-year-old Frances Goldin, who said society allows discrimination against gays and lesbians. She said her two daughters were marching in the parades in Portland, Ore., and San Francisco. Goldin said people had approached her with their phone numbers, asking: "Can I adopt you as my mother?"

She said she'll call them. "Difference enriches us all," she said.