Aer Lingus said it carried 1.117 million passengers in July, 8.2% more than the same time last year.
Short-haul passenger numbers rose by 11.2% to 1.004 million while its long-haul passenger numbers fell by 12.4% to 113,000.
The airline's load factor - a measure of how full its planes are - fell to 82.3% from 83.3% the same month a year earlier. Its short-haul load factor was 85.6%, up 0.4 percentage points as capacity rose by 12.8%.
Aer Lingus said its long-haul load factor fell 4% to 77% with capacity falling by 12.7%.
Shares in Aer Lingus closed just over 1% higher at 49 cent this evening.
