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NIH Exploratory/Developmental Research Grant Award (R21)


The R21 grant mechanism is intended to encourage exploratory/developmental research by providing support for the early and conceptual stages of project development. The NIH has standardized the Exploratory/Developmental Grant (R21) application characteristics, requirements, preparation, and review procedures in order to accommodate investigator-initiated (unsolicited) grant applications.

The R21 Parent funding opportunity for investigator-initiated R21 applications can be found on the Parent Announcements (For Unsolicited or Investigator-Initiated Applications) page; and articulates the policies and procedures that apply to this grant mechanism.

This website describes the use of the R21 and describes the NIH Institutes and Centers (ICs) that intend to accept such applications.

Application Characteristics

  • You may request a project period of up to two years
  • The combined budget for direct costs for the two year project period may not exceed $275,000. No more than $200,000 may be requested in any single year.
  • The R21 can not be renewed
  • No preliminary data are required but may be included if available.
  • The Research Strategy may not exceed 6 pages.


  • Exploratory, novel studies that break new ground or extend previous discoveries toward new directions or applications.
  • High risk high reward studies that may lead to a breakthrough in a particular area, or result in novel techniques, agents, methodologies, models or applications that will impact biomedical, behavioral, or clinical research.
  • Projects should be distinct from those supported through the traditional R01 mechanism.

Projects of limited cost or scope that use widely accepted approaches and methods are better suited for the R03 small grant mechanism (see R03 announcement citation).

All investigators should consult the list of participating ICs in the funding opportunity to which they are applying to determine if an R21 application is appropriate. Investigators are strongly encouraged to consult with the appropriate NIH program administrator about their proposed research project during the concept development stage of the application.

All R21 grant applications will be assigned to the ICs according to standard PHS referral guidelines and specific program interests. Applications that are assigned to an IC that does not participate in this program may be returned without review.

There is also a list of ICs that do not accept unsolicited R21 applications. Non-participating ICs might solicit other R21 applications using Requests for Applications (RFAs) or Program Announcements (PAs) to meet specific program needs. Information about such initiatives can be obtained in the NIH Guide for Grants and Contracts and by consulting with NIH staff. In some cases those announcements may specify different application characteristics, review criteria, and receipt dates.

Due Dates

  • Standard receipt dates are February 16June 16, and October 16. AIDS and AIDS-related grant application due dates are May 7, September 7, and January 7. For additional information, the receipt, review and award cycle schedules are posted on standard due dates.

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Active Funding Opportunities