Employers value what they pay for (or is it pay for what they value?): unpaid interns are no more likely to get a job offer than students who don’t do internships; paid interns improve their odds by over 50%. From a US survey:

60 percent of 2012 college graduates who took part in paid internships received at least one job offer…

…unpaid interns fared only slightly better in getting job offers than graduates who had not taken part in an internship. Thirty-seven percent of unpaid interns received job offers; 36 percent of graduates with no internship experience received job offers …

Since the survey can’t really tell the difference, statistically, between 37% and 36%, the press release’s “slightly better” is being too kind to unpaid internships. The full study is behind a paywall, but its executive summary says it better (emphasis added):

The unpaid internship offers no advantage to the job-seeking student.

More from the press release:

Paid interns spend much of their time engaged in ‘real’ work; employers prize that kind of hands-on experience. Conversely, unpaid interns spend more time on clerical tasks and less on the type of duties that employers value.