"It's real busy in the house, we are in the final, frenzied hours now," said Academy of Motion Pictures Arts and Sciences spokesman John Pavlik at the Oscar show's buzzing venue, Hollywood's Kodak Theatre.
Some 3,300 VIPs, including the world's biggest stars, were due to begin arriving at the foot of the massive crimson carpet at 3:30 pm (1130 GMT Sunday) to be greeted by a blaze of flashbulbs and the screams of 300 hand-picked fans.
The arrivals ceremony, which like the Oscars is watched by up to a billion television viewers across the globe, is considered by many to be the greatest fashion show on earth.
Celebrities parade down the carpet - lined with giant Oscars statuettes, hundreds of journalists and a bleacher full of fans - in designer gowns, wearing millions of dollars worth of diamonds and jewels.
"Whatever happens in the awards show, this is the time when the whole world can see their most beautiful and glamorous icons in a pageant fit for Hollywood royalty," said awards expert Tom O'Neil.
This year's Oscars ceremony, to be hosted by racy and irreverent comedian Chris Rock, has undergone a facelift in a bid to woo new viewers.