And it's not the first time members of Unite Here have walked off the job.
The union representing hospitality workers has been working without a contract for 20 months.
"Hyatt, a company run by billionaires, wants to outsource work and impose dangerous working conditions on housekeepers. Workers also say they want to be able to show solidarity with Hyatt workers elsewhere. Under Hyatt's current terms, they would be forced to waive their right to do so," a news release from UniteHere says.
Hyatt says it's been negotiating in good faith and that Monday's walkout will not have an impact on operations.
"It is unfortunate that less than a week after a major trade show pulled out of Chicago, citing labor issues and high costs, that UniteHere would stage this production," a Hyatt news release said.