"Cosmopolitan, look around, Las Vegas is a union town!" protesters yelled, the Las Vegas Sun reported Thursday.
The protesters included about 100 members, wearing red T-shirts, of the Culinary Union Local 226 sitting down on Las Vegas Boulevard.
The protesters were arrested and led away in a scene that lasted about an hour as 1,000 union members from various resorts were nearby holding signs. Scores more watched from an overpass.
"Cosmopolitan workers are not second-class citizens ... They need a contract," said Maria Mares, a 50-year-old housekeeper of the Riviera.
The union contract at Cosmopolitan expired two years ago. The points of contention involved wages, healthcare benefits and job security, the newspaper said.
Talks with the union are "ongoing," said Cosmopolitan spokeswoman Amy Rossetti.
But union members said they were frustrated with the negotiations.
"We'll be back," protesters chanted as they were taken away by police.