The Kansas City Federal Reserve's monthly composite services index fell to a reading of minus 3 in August after rising to 14 in July, suggesting contraction.
Expectations were for a smaller decrease to a reading of 10 in a survey compiled by Bloomberg.
The other regional services measures already released have moved generally lower.
There was a decrease in the Kansas City revenue/sales reading to 0 from 19, while the employment reading fell to minus 4 from 4.
The reading of selling prices decreased to 8 from 12, while the input price index rose to 46 from 45. A reading above zero indicates growth.