In the winter capital of America's high society, only one thing is in short supply these days - debutantes.

The Palm Beach Opera Debutante Cotillion on Thursday night was canceled for the first time in its 30-year history after only six young women signed up for the coming-out party at the elegant Breakers Hotel. Usually, 20 to 30 take part.The cancellation left a void in Palm Beach's social calendar. The city of 10,000 with its palm-lined boulevards, marble mansions and manicured estates can triple its population at the height of "the season," when the rich come south for the weather, the scenery and the social whirl.

"A lot of people are very sad about this," said Sunny Miller, chairwoman of the event for more than a decade. "If we'd known how sad we were going to be, we would have had it with just the six."

Instead of coaching anxious girls in rehearsals in the Venetian ballroom of the Breakers - the 1927 Italian Renaissance structure that has long been the social center of a very social town - and attending the flurry of family parties that fill the holidays, Mrs. Miller was explaining what happened to the debutante ball.

The popularity of the debutante experience may have waned "because there is a stigma attached to it," said Judy Persin, whose daughter would have been at this year's ball. "They think you have to be wealthy, be in the blue book."

She added: "The `coming out' part of it is kind of passe."

So Thursday night saw no presentation of debs in gowns, pearls and long white gloves. No orchestra playing a waltz. No proud fathers. No bouquets of red roses. No young men in white tie and tails. No whirlwind of parties from Thanksgiving to New Year's Day.

Participation in the Palm Beach cotillion can cost from $2,500 to 20 times that, Mrs. Miller said. Some debutantes' parents put on parties that cost $50,000 or more. The debutantes - ages 16 to 23 - are chosen by a committee from names recommended by friends and former participants.

Margaret Beuttenmuller, a high school senior and former deb, said many of her friends didn't understand the concept. "The big thing about it for me was the amount of time I got to spend with my whole family . . . a lot of time to spend with my dad, who is very busy working," she said.