Aer Lingus carried a total of 815,000 passengers - including those on its regional services - in March.
This was a 2.3% increase on the number of people it carried in the same month last year.
The airline said its short haul traffic was down marginally last month to 625,000 from 628,000.
But its long haul passenger numbers were up over 25% to 94,000 from 75,000 last year as Aer Lingus introduced a number of new routes to the US in the last year.
Aer Lingus said its load factor - how many seats it fills on each flight - rose to 79.1% from 74.7%. Its short haul load factor grew by 2.5 percentage points to 76.4% while its long haul load factor rose by 6.5 percentage points to 82.6%.
The number of passengers on its regional services - operated by Stobart Air - rose by 2.1% to 96,000 from 94,000.
Yesterday, Ryanair reported a 28% increase in passenger numbers for March to 6.67 million. This resulted in its share price jumping to over €11.
