The possible disruption is due to a demonstration that is being held in Brussels by the European Federation of Transport Workers. The level of disruption is dependent on how many baggage handlers from Zaventem take part.
The company that runs the airport advises passengers to check with their airline before setting off.
The largest airline operating out of Zaventem, Brussels Airlines place a warning message on its website on Tuesday evening advising passengers of possible disruption. Aviapartner and Swissport provide baggage handling services at Zaventem.