In some instances a protocol involving human subjects must be terminated earlier than anticipated because of concerns about the safety of subjects (perhaps due to one or more serious or unexpected events). A study might also be terminated if it has reached a statistically valid conclusion with fewer-than-expected subjects, or if the study is extremely unlikely to ever reach a statistically valid conclusion (perhaps due to poor subject recruitment or retention or an unfavorable conditional power calculation). Whenever a study is terminated, it is the investigator’s responsibility to bring closure to the study. In some studies this may mean weaning a subject off a drug or removing an implanted device. In other cases it will mean debriefing subjects and/or notifying them by phone, letter, or during a clinic visit. The rationale for terminating the study should be provided to all subjects, and their questions or concerns should be addressed. If the IRB terminates the study because of serious adverse or unexpected events (or for other reasons), the HHS OHRP must be notified. The OHRP will review the rationale for the early termination and provide feedback to the IRB.