The Academy, anticipating bad weather, had a large tent constructed on the red carpet to keep nominees dry.
Asking about the designer outfits of the actresses is a regular question on the red carpet but many tried to buck the trend as #askhermore started trending.
Gaga, who gave an amazing maiden performance at the Oscars, looked stunning in couturier Azzedine Alaia's plunging white gown that stole the spotlight. The newly engaged star hid her ring in huge red gloves.
The figure-hugging dress featured intricate white beading from top to bottom, a halter neckline and sexy keyhole cut-out. This was the '12 Years A Slave' actress' second outing at the Oscars.
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Jessica Chastain had navy blue double-layered dress with a high slit similar to Sienna Miller's brooding dark blue Oscar de la Renta gown with thin straps.
Best supporting actress winner Arquette opted for a one-shoulder black-and-white gown by Rosetta Getty which she paired with a Ferrgamo clutch and shoes.
French beauty Cotillard, nominated for Best Actress for her role in "Two Days, One Night", stunned in a white Dior gown with black details.
Another best actress nominee, 'Wild' star Reese Witherspoon wore an off-shoulder blue-and-white gown by Tom Ford at the Oscars red carpet. She looked elegant with her lustrous golden locks untied.
British actress Felicity Jones, a best actress nominee for her role in "The Theory of Everything", donned an Alexander McQueen silver gown. She kept her hair and make-up sleek and simple, a perfect complement to her voluminous dress.
Dakota Johnson too wore a bright red Saint Laurent dress while Margot Robbie sports a black dress by same label.
Jennifer Lopez wore a nude, deep V-neck, gown from Elie Saab.
Actors too went for different colours rather than sticking to black. "Selma" star David Oyelowo wore a burgundy tuxedo from Dolce&Gabbana, best actor nominee Eddie Redmayne opted for a midnight blue Alexander McQueen tux while fellow countryman Benedict Cumberbatch turned up in white.
But it was last year's best supporting actor winner Jared Leto's lilac tux that sparked maximum debate.