A Beautiful Mindhas won the Best Picture Oscar after beating off Lord Of The Rings, Gosford Park, Moulin Rougeand In the Bedroom.
Ron Howard won the Best Director Oscar for A Beautiful Mind. It is the first time he has won the award.
Peter Jackson, David Lynch, Robert Altman and Ridley Scott were the other directors in the category.
The film's lead actor, Russell Crowe, missed out on Best Actor to Denzel Washington, who was honoured for his role in Training Day. Tom Wilkinson, Will Smith and Sean Penn had also been nominated.
Best Actress Oscar went to Halle Berry for her role in Monsters Ball. She is the first African-American actress to win the award in 74 years.
Berry won a standing ovation from the audience and immediately burst into tears."This moment is so much bigger than me" she said. "I am so honoured".
Later Washington noted Berry's fellow success as a black actor, telling the audience: "Two birds in one night, huh?"
Best Supporting Actress went to Jennifer Connelly for A Beautiful Mind, while Britain's Jim Broadbent's performance in Iriswon him Best Supporting Actor.
Shrektook the Best Animated film award.
The Irish short animated film Give Up Yer Aul Sins, which was made by Brown Bag Films, failed to win an honour.
