Exclusion criteria are a set of predefined definitions that is used to identify subjects who will not be included or who will have to withdraw from a research study after being included. Together with inclusion criteria, exclusion criteria make up the eligibility criteria that rule in or out the participants in a research study. Similar to inclusion criteria, exclusion criteria are guided by the scientific objective of the study and have important implications for the scientific rigor of a study as well as for assurance of ethical principles. Commonly used exclusion criteria seek to leave out subjects not complying with follow-up visits, those who are not able to provide biological specimens and data, and those whose safety and ethical protection cannot be assured.

Some definitions are ...