Staff at CityJet Handling Ltd picketed Dublin Airport this morning in what union officials describe as a dispute over pay and conditions.
The company, which is separate from CityJet airlines, controls check-ins and handles the baggage for a number of airlines including Air France, Aer Aran Express, British European Airlines, Air Wales and CityJet.
A spokesman for the company claims the dispute is about union recognition saying: "There is no union recognition in CityJet Handling as the majority of staff have constantly opted for the current internal system, rather than have a third party negotiate on their behalf."
SIPTU say they represent over 90 per cent of the 120 workers at the company.
The strike is expected to continue for 24 hours.
A spokeswoman for Aer Rianta said so far no services have been affected.