Describes the typical recent cycle; last reviewed 2026-08-07. The official call is the authority on current dates and amounts.
About the NIH R21 Exploratory/Developmental Grant
The R21 funds exploratory, early-stage work: novel methods, risky hypotheses, new directions — projects where the point is to generate the evidence that something is worth a full R01. Preliminary data are explicitly not required, which is the mechanism’s whole reason to exist.
The trade-off is size: two years and $275k total direct costs disappear quickly, and R21 success rates are often no better than R01 rates at the same institute. Treat it as a strategic instrument — the pilot that de-risks the big grant — rather than a starter R01.
Who can apply
Same institutional eligibility as the R01; any career stage.
Not all NIH institutes accept parent R21s — check the participating-institutes list on the announcement.
No preliminary data required (though reviewers rarely object to some).
Writing a competitive application
Frame the project as genuinely exploratory — an R21 that reads like a shrunken R01 gets criticized as under-resourced rather than praised as bold.
Deliverables should be decision-grade: what will exist after two years that changes what gets funded next?
Check the institute’s funding statistics first; at some institutes an ESI R01 is the statistically better bet than an R21.
Scale and expectation: the R01 funds a mature, well-evidenced project for up to five years; the R21 funds two years of higher-risk exploration with a $275k total direct-cost cap and no preliminary-data requirement. R21s are for establishing feasibility; R01s for delivering the science.
Do R21 grants renew?
No — the R21 is not renewable. The intended path is R21 results feeding a subsequent R01 (or other mechanism) application.