Growth in the country's services activity picked up slightly in August, although firms' expected levels of activity in 12 months' time slipped to the lowest level in 12 months.
The Investec Services Purchasing Managers' Index (PMI) rose to 58 from 57.4 in July, when it had touched the lowest level since a weather-affected March.
The index has stood above the 50 mark that separates growth from contraction for six years in a row.
The services sector covers areas as diverse as communication, financial and business services, IT and the tourism trade.
While strong growth in new orders remained steady for the third successive month, the rate of expansion in those coming from abroad slowed to a five-month low and the sub-index measuring expectations fell to 69.1 from 71.4 a month earlier.
That was only the sixth time in five years that the business expectations index has fallen below the 70 mark.
A survey on Monday showed that manufacturing activity gained momentum over the summer with sharp increases in new orders and output recorded in August.
"Looking ahead, although the business expectations index slowed to its lowest level since October last year, its level is consistent with strong optimism amongst service sector firms," Investec Ireland's chief economist Philip O'Sullivan said.
"Considered alongside the manufacturing PMI report, this week's PMI releases suggest that the rate of growth in activity across much of Ireland's private sector remains strong," Mr O'Sullivan added.