The Institute for Supply Management's services index eased to 60.1 in May, in line with forecasts and down from 63.0 in April.
A number above 50 indicates growth in the sector.
The survey's prices-paid index spiked to 77.5 from 70.5, while the jobs component rose to 58.0 from to 56.5. Demand for new orders slipped to 59.6 from 64.6.
The services sector makes up about 80 percent of U.S. economic activity, including businesses like restaurants, hotels, hair salons, banks and airlines.
