Joel and Ethan Coen swept the board last year with No Country For Old Men
The first round of voting for the Oscars has begun after ballot papers were posted to members of the Academy of Motion Picture Arts and Sciences.
Some 5,810 voting members will decide which actors and films will be nominated ahead of an official announcement on 22 January.
A second round of voting will then begin to decide who will be announced as the 2009 winners on 22 February.
This year's awards will be hosted by Australia actor Hugh Jackman.
Early front-runners for best film include Mumbai-set drama Slumdog Millionaire, directed by British director Danny Boyle.
Frost/Nixon is in the frame for next year's Oscars
The Curious Case of Benjamin Button, starring Brad Pitt, is also tipped for the top prize.
Membership of the Academy of Motion Picture Arts and Sciences is made up of actors, directors and other professionals from across the industry.
The voting papers were sent out on Tuesday and must be returned by 12 January to count towards nominations.
Last week, nominations were announced for the 2009 Screen Actors Guild (SAG) awards - one of the key indicators for Oscar success.
British actress Kate Winslet was shortlisted in two categories, as best actress for Revolutionary Road and best supporting actress for post-war drama The Reader.
Political biopic Milk and play adaptations, Doubt and Frost/Nixon, were among films shortlisted for the SAG best ensemble award - its equivalent of a best picture prize.
On Tuesday, SAG, which has 120,000 members, postponed its vote on whether to go on strike.
It had wanted to ballot members on 2 January but will not now do so until 14 January at the earliest, because of division among its members.
The union objects to studio plans to make one-off rather than residual payments to actors in shows made for the internet.
Any strike action could cripple the Oscar ceremony, with actors unlikely to cross picket lines.