Aer Lingus is to suspend services on its route from Dublin to Los Angeles from November.
The airline has also announced plans to cut its capacity on long-haul US routes by 15% this winter.
Aer Lingus Chairman John Sharman will tell the airline's shareholders this afternoon that the move is due to higher fuel costs, a weak US dollar and the economic slowdown.
He also warns that Aer Lingus expects 'at best', to break even this year because of high fuel prices and the uncertain economic outlook.
The decision to cut capacity will see the long-haul fleet remain at the current level of nine in 2009, although new planes will replace older aircraft.
Aer Lingus will also refurbish three of the current long-haul fleet, but warned that this would affect the frequency of services to the US in the first three months of next year.
Separate figures released today show that, so far this year, the airline is filling only about two-thirds of its seats on US routes.