Using the PRS API for XML Upload: Cleaning Up Your Data
ClinicalTrials.govUsing the PRS API for XML Upload: Cleaning Up Your Data. NLM Tech Bull. 2026 Sep-Oct;(472):e4.
September 22, 2026 [posted]
Background
The Protocol Registration and Results System (PRS) is a data submission portal used by organizations to submit clinical research studies to ClinicalTrials.gov. Study data can be entered directly within the PRS user interface (UI) or created offline as an XML file and then uploaded. The information submitted to the PRS is available to the general public on ClinicalTrials.gov.
For large organizations, manual data entry for dozens or hundreds of trials is not practical. To support those organizations, ClinicalTrials.gov developed the PRS application programming interface (API). The PRS API automates the transfer of data directly from an organization’s internal database to the PRS. It reduces manual data-entry errors, helps meet compliance timelines, and enables bulk processing of multiple study records. An organization can facilitate timely updates to study status information to the public ClinicalTrials.gov website by integrating its clinical trial management system with the PRS through the API.
To demonstrate the popularity of the XML Upload API, a monthly average of 393,000 XML uploads were performed during the five-month period from September 2025 to January 2026. In addition, between March and June of 2025, the XML Upload API was used by 219 organizations to facilitate study record uploads to the PRS.
XML Upload API Utilization and Validation Standards
The API relies on specific XML schemas to validate data. If the API upload includes tags that do not align with these schema rules, the submission is rejected. ClinicalTrials.gov regularly reviews the existing XML schemas to identify obsolete fields and encourage organizations to align their submissions with current database standards. This keeps our data pipeline fast and accurate.
The PRS XML is described in Section 9 of the PRS User’s Guide with the links to two XSD files: ClinicalTrials.gov PRS Protocol Schema and ClinicalTrials.gov PRS Results Schema. This article discusses updates to the ClinicalTrials.gov PRS Protocol Schema and recommended steps for organizations that use the XML Upload feature to submit studies.
Removing Deprecated XML Data Elements
During the long evolution of ClinicalTrials.gov, we accumulated data elements that no longer need to be submitted. Some of these were introduced under the Food and Drug Administration Amendments Act of 2007 (FDAAA) to identify probable applicable clinical trials (pACTS), but are not needed for this purpose anymore. The PRS still accepts these data elements to maintain backward compatibility with legacy systems, but they are no longer processed, stored, or displayed. Removing these data elements will streamline your XML payloads, reduce confusion for your development team, and prepare your systems for future schema updates when these fields may be permanently removed. If your organization uses the PRS API or XML Upload feature to submit studies, we recommend updating your XML generation software to remove the thirteen deprecated data elements listed below.
Deprecated fields:
| Type of Field | PRS Data Elements | Suggested Action |
|---|---|---|
| FDA fields |
|
Remove entirely. |
| Date field |
|
Remove end_date. Use last_follow_up_date (Line 218) instead. |
| Contact fields |
|
Remove these individual elements. Put the information about ReponsibleParty into the elements: investigator_username, investigator_title, and investigator_affiliation (Lines 363–365). |
| Study Design fields |
|
Remove entirely. |
| Outcome Measures field |
|
Remove entirely. |
Resources and Recommendations for API Users
In summary, to align your system with the updates to the current schema, we recommend the following actions:
- Download the latest PRS Protocol Schema to use as a reference.
- Remove the deprecated tags listed above from your XML generator and use the replacements where noted.
- Test your changes using the PRS Test system.
- Sign up for emails from ClinicalTrials.gov PRS News and Updates to receive updates about topics such as technical changes to the system, new and updated support materials, and PRS-specific events such as training opportunities.
The PRS API serves an important role in enabling organizations to programmatically manage large volumes of clinical trial record data with speed and accuracy. To ensure your automated data pipelines remain robust and efficient, we encourage all API users to keep their systems up to date.
For questions or technical assistance, please contact the PRS Help Desk at register@clinicaltrials.gov.