As they stride down the catwalk with their long, slender legs, they seem almost perfect and in a way untouchable, these young women who will be showing off the creations of the top couturiers during the New York Fashion Week.
But now these much-admired models who are participating in the fashion week that started Friday - for many years icons for millions of women - are having a critical eye cast on them.
"How thin is too thin - and how thin is potentially fatal?" is the question on many lips.
The death from anorexia of Brazilian supermodel Ana Carolina Reston at the age of 21 has caused consternation in the fashion world.
Just as sad was the case of Luisel Ramos, who broke down with heart failure at the age of 22 during a show in Montevideo, after she had recently lost a full 12 kg.
In Italy and Spain measures have been taken to keep over-thin models off the ramp, and the theme has become a hot topic in the US fashion industry.
The industry does not want young women to starve themselves to become a "parade of skeletons", as Italian designer Valentino Garavani has put it.
Three weeks before the New York Fashion Week, the Council of Fashion Designers of America (CFDA), which represents 280 influential designers and is headed by Diane von Fuerstenberg, published a set of guidelines.
There has been long discussion ahead of this "health initiative" on whether there should be a ban on underweight models with a Body Mass Index of under 18. The BMI is calculated by dividing the mass of the body in kilograms by the square of the height in metres.
The World Health Organisation regards a BMI of under 18.5 as indicating underweight.
But the CFDA in the end decided not to press the issue, saying the intention was not to impose controls but to raise consciousness over the issue.
Some models were by nature thin, while eating disorders were complex and often had a psychological or social background, it said.
In concrete terms this means that the modelling industry is not to blame.
The CFDA instead issued recommendations that anorexic models should receive professional help and be told about the dangers of starvation in workshops. And backstage there should be sufficient healthy snacks for the models to enjoy.
Models should also not be under the age of 16 and models younger than 18 should not work after midnight.
There is thus no ban on skinny models at the New York Fashion Week this year. Any such ban would have rendered many of the girls and their agencies unemployed.
One US survey put the average BMI for top models at 16.3.
Cathy Gould of the Elite modelling agency in North America expressed understanding for the Madrid decision, but added that measures of this kind would be "discriminatory" in the case of models that are extremely slim by nature.
David Bonnouvrier, head of DNA Models, takes a different view.
"I am kicking and screaming about it now because this should be an industry of beauty and luxury, not famished-looking people that look pale and sick," he told the New York Times. "We are minutes away from a catastrophe."
The message appears to be getting through - albeit slowly.
Linda Wells, editor of the magazine Allure, says: "What becomes alarming is when you see bones and start counting ribs."
Even supermodel Jessica Stam has expressed concern. "I don't know if they are healthy or not but I don't think the frail, fragile look is very feminine, and I don't think it's attractive," the 20-year-old Canadian says.
There are many who think like Stam. But Reston weighed just 40 kg on her diet of tomatoes and apples just before her death and was nevertheless photographed for the Armani Catalogue.
By the time her agency L'Equipe sent her home it was too late.
The stars, fashion scouts and stylists joining the rich in the front rows at the Fashion Week will not be able to discern how many of the catwalk models they are watching are suffering from eating disorders.
But perhaps they could take the time to visit the exhibition Dangerous Beauty in the Chelsea Art Museum.
Here a critical look is taken at how the beauty ideal is manipulated for mass consumption by means of exhibits that are sometimes shocking.
Those entering the exhibition first have to walk across a floor covered with bathroom scales.