As of July 15, 2012, Iowa Research Online has had over 1,000,000 download of items. This means there have been 1,000,000 uses of University of Iowa faculty, staff and student created or supported content in the just over 3.5 years since IRO launched (January, 2009). More than half of this use occurred in the last 12 months.
The most used series are:
| Series | Total Use | Percent of Total |
| Theses and Dissertations | 451,428 | 44.85% |
| Walt Whitman Quarterly Review | 116,955 | 11.62% |
| Medieval Feminist Forum | 89,974 | 8.94% |
| Poroi | 39,659 | 3.94% |
| Political Science Publications | 38,644 | 3.84% |
| Iowa Geological Survey Annual Report | 22,867 | 2.27% |
| Electronic Journal of Africana Bibliography | 20,921 | 2.08% |
| The Educational Weekly | 19,478 | 1.94% |
| Iowa Short Fiction Award & John Simmons Short Fiction Award | 18,012 | 1.79% |
| G. R. Boynton’s New Media and Politics | 17,849 | 1.77% |