Second-quarter U.S. staffing revenue at Robert Half International Inc. (NYSE: RHI) rose 16.9 percent year over year to $672 million. But international staffing revenue fell 4.7 percent to $246 million.

The company said international staffing revenue would be up 3.3 percent if adjusted for constant currency and the same number of billing days.

“Our growth rates outside the United States were not as strong, owing in large measure to ongoing concerns over the European debt crisis,” Harold “Max” Messmer Jr. said in a conference call with analysts. “Our business has limited exposure to the hardest hit countries in Europe, but we did feel some of the effects of a more cautious business environment and lower currency exchange rates in Europe and other parts of the world.”

Robert Half’s global second-quarter revenue rose 9.6 percent to $1.03 billion in the second quarter from $938.0 million in the second quarter of last year.

Second-quarter gross margin improved to 40.4 percent from 39.7 percent in the year-ago quarter. The company saw an increasing mix of permanent placement and temp-to-hire revenue, Messmer said.

Robert Half posted net income of $45.3 million, up 24.4 percent from $36.4 million in the same period last year. Net income was reduced by $8.1 million in the most recent quarter as the result of a settlement to litigation. Robert Half had recently announced a settlement deal in three wage-and-hour cases in California, for the story click here.

The company estimates third-quarter revenue of between $1.01 billion to $1.06 billion, a year-over-year increase of between 2.6 percent and 7.6 percent.

Robert Half, based in Menlo Park, Calif., ranks as the ninth-largest staffing firm in the world.