There were 3.97 million open positions in April, down from 4.07 million in March, according to the government's Job Openings and Labor Turnover Survey (JOLTS). The hiring rate dipped to 3.0 percent from 3.1 percent.
Private-sector hires slipped to 3.71 million from 3.81 million, and the rate eased to 3.4 percent from 3.5 percent.
The level of total hires has risen from a trough of 3.6 million in October 2009 but remains well below the 5.0 million that prevailed before the economy entered a prolonged recession at the end of 2007.
Data last week showed the economy added a disappointing 54,000 new jobs in May and the unemployment rate rose to 9.1 percent, sparking worries the recovery might be faltering.
The JOLTS figures encompass employment data from about 16,000 establishments across the country.
(Reporting by Pedro Nicolaci da Costa; Editing by Kenneth Barry)