Aer Lingus carried a record 1.13m passengers last month, an increase of over 7pc compared to the same period last year.
The airline's mainline traffic - which excludes services operated by Aer Lingus Regional - rose from 1.06m to 1.13m during August, a 7.3pc rise.
On services to North America, which are almost entirely accounted for by routes to the United States, Aer Lingus carried 173,000 passengers, 16.9pc more than it did in August last year.
Its short-haul services to the UK and Europe carried 965,000 passengers, which was 5.7pc more than in July 2014.
The load factor at Aer Lingus last month, or the percentage of available seats it filled, was 90.3pc. That was 2.5 percentage points higher year-on-year.
The load factor on transatlantic services dipped 0.7pc to but remained very high at 93.4pc while the load factor on short haul flights rose by 4.4pc to 87.9pc.
Total passenger numbers for the month, including Aer Lingus Regional flights which are operated by Stobart Air rose from 1.2m to 1.27m.
Aer Lingus was formally acquired by British Airways owner IAG earlier this week.