Professional employer organization revenue at Automatic Data Processing Inc. (NASD: ADP) rose 15.1% year-over-year to $378.5 million in the company's fiscal third quarter ended March 31.

The number of PEO worksite employees at the end of the third quarter was 205,000, up 6.2% from 193,000 when the third quarter of the last fiscal year ended.

ADP estimated PEO revenue to rise 8% to 10% in this fiscal year.

PEO services represent just one of Roseland NJ-based ADP's lines of business, which include nonstaffing services. Total third-quarter revenue at ADP was $2.44 billion, up 3.1% from a year ago.