Not all clinical trials will lead to publication in a scholarly journal. However, many government, funding, and publishing organizations require that clinical trials be registered in a publicly available registry. These registries allow users to search for information about clinical trials that are in varying stages, regardless of the results of the trial or if they end up being published in a scholarly journal.
The information contained in these registries is one example of "grey literature". Searching for clinical trials information in these registries is an important part of the research process, especially the comprehensive searching required for systematic reviews, as it provides a fuller picture of the evidence available, outside the bias possible in the publication process. For more information on searching for grey literature, check out our Systematic Reviews Guide.
Registered clinical trials will typically provide basic information about the study, including the disease and intervention(s) being studied, a description of the study design, the location and contact information for the study, and possibly results of the study once it has been completed.
Please note: Being registered on one of these websites is not an indication that the organization has evaluated or approved of the research.
Though not officially recognized registries, the following websites provide the ability for users to search for clinical trials that meet specific criteria.