A new standard for sequence listings – WIPO Standard ST.26

by Dr. Markus Grammel and Dr. Elena Biselli | 26. June 2022 | Know-How


A new global sequence listing standard of the World Intellectual Property Organization, the WIPO Standard ST.26 (WIPO ST.26), will come into force on 1 July 2022. On this date, all WIPO member states will implement simultaneously the new standard at the international, regional and national levels. Let’s have a look at the main changes.


Patent applications in the life sciences regularly disclose nucleotide and amino acid sequences that must be provided to patent offices in the form of a sequence listing, which is a standardized representation of the sequence information, to enable patent offices to conduct a search on these sequences.

The current standard for sequence listings, which determines the format and content of the sequence listing, is WIPO Standard ST.25 (WIPO ST.25). WIPO Standard ST.25 is often interpreted differently by patent offices around the world and it is not aligned with the structure of current public databases of nucleotide and amino acid information. With the aim of addressing these perceived shortcomings, WIPO now introduces the new standard ST.26.

Date of entry into force of WIPO Standard ST.26

New WIPO ST.26 enters into force on 1 July 2022 (the so-called “Big Bang” date). In general, WIPO ST.26 will apply to all patent applications filed on or after 1 July 2022. This means that for any patent application that is filed on or after 1 July 2022 a WIPO ST.26 compliant sequence listing has to be included if the application contains relevant sequences. Note that the Committee on WIPO Standards decided that the filing date is the relevant date, not the priority date. The new standard will therefore apply for applications filed on or after 1 July 2022 that have a priority date before 1 July 2022. Patent applications with a filing date before 1 July 2022 have to continue with WIPO ST.25. The requirements with respect to divisional applications is a matter of national laws.

While WIPO ST.26 is introduced to achieve harmonization between patent offices, it already emerges that the actual practice, at least for divisional applications, will differ from patent office to patent office. For example, the European Patent Office (EPO) prescribes WIPO ST.26 compliance for any divisional application filed on or after 1 July 2022 (please see also Notice from the European Patent Office dated 9 December 2021 concerning the filing of sequence listings). The Intellectual Property Office of the United Kingdom on the other hand will not require WIPO ST.26 format for a divisional application, if the parent application was filed before 1 July 2022. In Germany, the updated regulations will require ST.26 compliant sequence listings for all patent applications, including divisional applications, filed on or after 1 July 2022 with the DPMA. Furthermore, the requirement to file ST.26 compliant sequence listings is extended to German utility models filed on or after 1 July 2022.

The main changes – an overview of WIPO Standard ST.26

The following lists some of the key changes between WIPO ST.25 and WIPO ST.26:

  • New WIPO ST.26 requires sequence listings in XML format.
  • Electronic filing of the sequence listing is the only formal correct filing possibility (no paper filing).
  • Sequences with D-amino acids, branched sequences and sequence with nucleotide analogs must be included.
  • Undefined residues (place holder residues ‘Xaa’ for amino acids, ‘n’ for nucleic acids) are not taken into account when determining whether the sequence meets the minimum length requirements for inclusion into the sequence listing (10 or more specifically defined nucleotides/4 or more specifically defined amino acids).
  • Sequences not meeting the minimum length requirements must not be included.
  • The molecule type of DNA and RNA sequences must be further described.
  • Uracil is indicated with a “t” instead of an “u” and amino acid sequences are indicated in one-letter code as opposed to three-letter code.
  • Applicant names and the title of the invention may be included in multiple languages. Other free text descriptors for sequences in the sequence listing may be included in up to two languages.

In order to adopt the new standard, amendments to the PCT are envisaged.

Furthermore, the WIPO has developed the new software ‘WIPO Sequence’ that applicants can use for the generation of ST.26 compliant sequence listings and conversion of sequence listings from ST.25 to ST.26. It is not mandatory to use this software. However, it is recommended to ensure compliance with ST.26.


ST.26 is very different and far more complex than to ST.25. An ST.26 compliant sequence listing may include information that would not be included in an ST.25 compliant sequence listing and vice versa. This can potentially lead to problems relating to added matter, loss of priority or loss of disclosure.


In view of the complexity of ST.26, we strongly recommend preparing these sequence listings well in advance to their filing to ensure compliance with all its requirements. Otherwise, applicants will have to pay a late furnishing fee to remedy the defects.


For divisional applications at the EPO and the GPTO, a conversion from ST.25 to ST.26 will be required, likely involving the applicant’s input and thorough attention to sequences that need to be included or might get excluded by the conversion to ST.26. It may even be advisable to file the existing ST.25 compliant SL along with a ST.26 compliant sequence listing to ensure that no disclosure is lost (or added in an irremediable way) in the conversion from ST.25 to ST.26. However, this will come at a cost, since any ST.26 non-compliant sequence listings filed on the filing date at the EPO will be taken into account in the calculation of the additional page fees.

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