The software maker filed paperwork for about 4,100 H-1B workers over 2010 and 2011, according to the study, published this week by the Brookings Institution. That's about 1.26% of all applications filed during the period.
IBM was second, with about 3,300 applications filed, while India-based TCS was third, with about 3,200 applications. Deloitte Consulting, with 3,000 applications, was fourth, and India's Wipro rounded out the top five, at 2,900.
Brookings data shows that, while 70,000 employers applied to hire H-1B workers in 2010-11, the top 25 companies, mostly tech firms, accounted for more than 12% of the applications.
[ Will Microsoft's management practices--not its competitors or its products--be the cause of its decline? See Microsoft A Victim Of Its Own Success. ]
"A small number of companies were very heavy users of the program," the study's authors noted. "The employers requesting the most H-1Bs are large private companies specializing in information technology, consulting, and electronics manufacturing."
In addition to tech companies, the top 25 included retailer CVS and financial services giants Goldman Sachs and JPMorgan Chase.
To hire an H-1B worker, employers must receive approval from U.S. Citizenship and Immigration Services. The visas, which are reserved for workers in what USCIS calls "specialty occupations," are good for three years and can be renewed for an additional, three-year period.
The program isn't without controversy. Critics say U.S. companies should not be importing labor at a time of high unemployment. Backers say the country faces an IT worker shortage, and that H-1B employees help fill the gap.
The program is limited to 65,000 visas per year, plus an additional 20,000 for workers who hold an advanced degree from a U.S. college or university.
Microsoft officials have long maintained that the cap needs to be raised or eliminated altogether. Testifying before Congress in 2008, Microsoft chairman Bill Gates said the cap "bears no relation to the U.S. economy's demand for skilled professionals."
As of June 1, the government had issued 55,600 standard H-1B visas out of the annual allotment of 65,000 for next fiscal year, according to USCIS. The feds also issued 18,700 H-1B visas reserved for graduates of advanced degree programs in the United States.