May 2022 | No. 05/2022


Reminder about the Filing of International Applications Containing Sequence Listings in WIPO Standard ST.26 Format

It is recalled that WIPO Standard ST.26 (“ST.26”) should be used for disclosing nucleotide and amino acid sequences in international applications filed on or after 1 July 2022.  Compared to WIPO Standard ST.25 (“ST.25”), the new standard includes additional sequence types and is more consistent with the requirements of major sequence databases.  This should assist both the preparation of sequence listings and the availability of sequence data for searching.

Any disclosure of sequences in an international application filed before 1 July 2022 must continue to comply with ST.25, both at the time of filing and with respect to any listings submitted subsequently.  However, any disclosure of sequences in an international application filed on or after 1 July 2022 must comply with ST.26, even if the priority application contains an ST.25 sequence listing. 

You should be aware that it is very important to use the standard which applies on the date of filing your international application.  ST.26 sequences include mandatory qualifiers that may require content different from the qualifier text in ST.25.  Consequently, while submitting a sequence listing using the wrong standard is a formality defect (whether ST.26 for an international application filed before 1 July 2022 or ST.25 for an international application filed on or after that date), it may be difficult or impossible to correct that defect or to amend the application to use the correct standard without adding subject matter.

If you intend to file your international application on or after 1 July 2022, you should download the WIPO Sequence software from:  https://www.wipo.int/standards/en/sequence/index.html to transform your ST.25 sequence listing to ST.26 format well in advance of the proposed filing date.  Please note that WIPO has just released a new version of WIPO Sequence – for further information, please refer to “WIPO Sequence Version 2 Released with New Support Resources”.

For further information on migration to ST.26, please refer to the “Practical Advice” in PCT Newsletter No. 02/2022

You can also find further information on the implementation of ST.26 in the ST.26 FAQs at:


If you have any questions on ST.26 or the WIPO Sequence software, please contact the International Bureau at:  wiposequence@wipo.int