Ryanair grew traffic by 12% to 10.6 million passengers in May.
Load factor rose 2% percentage points to 94%.
Rolling annual traffic to May grew 16% to 108.5 million customers.
The airline said the growth had been achieved despite the impact of ATC strikes in France.
Meanwhile, Eastern European low-cost airline Whizz Air reported a 20% rise in passengers to nearly 2.2 million.
Load factors were up by 1.1 percentage points to 90.1%.
Rolling annual passenger numbers rose 19% to nearly 23.3 million.
