Entry into force
Main changes

A new global sequence listing standard of the World Intellectual Property Organization (WIPO) – WIPO Standard ST.26 (WIPO ST.26) – came into force on 1 July 2022. On this date, all WIPO member states simultaneously implemented the new standard at the international, regional and national levels. This article examines the main changes.


Patent applications in the life sciences industry regularly disclose nucleotide and amino acid sequences, which must be provided to patent offices, in the form of a sequence listing – a standardised representation of the sequence information. This enables patent offices to conduct a search on these sequences.

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

Entry into force

WIPO ST.26 entered into force on 1 July 2022. It applies to all patent applications filed on or after 1 July 2022, which 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. The requirements with respect to divisional applications are a matter of national law.

While WIPO ST.26 was introduced to achieve harmonisation between patent offices, it already seems that the actual practice, at least for divisional applications, will differ depending on the 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.(1) 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 German Patent and Trademark Office (GPTO). Furthermore, the requirement to file ST.26 compliant sequence listings is extended to German utility models filed on or after 1 July 2022.

Main changes

Some of the key changes between WIPO ST.25 and WIPO ST.26 are set out below:

  • The new WIPO ST.26 requires sequence listings in extensible markup language format.
  • Sequence listings must be filed electronically (paper filings are not possible).
  • Sequences with D-amino acids, branched sequences and sequences with nucleotide analogues must be included.
  • Undefined residues (place holder residues "Xaa" for amino acids and "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 or four or more specifically defined amino acids).
  • Sequences that do not meet 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 the conversion of sequence listings from ST.25 to ST.26. It is not mandatory to use this software, but it is recommended to ensure compliance.


ST.26 is far more complex than 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, applicants are strongly recommended to prepare sequence listings well in advance of 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 some patent offices (including 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 sequence listing along with a ST.26 compliant sequence listing to ensure that no disclosure is lost (or added in an uncorrectable 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 for the calculation of the additional page fees.

For further information on this topic please contact Markus Grammel at Grünecker by telephone (+49 89 21 23 50) or email ([email protected]). The Grünecker website can be accessed at


(1) See also "Notice from the European Patent Office dated 9 December 2021 concerning the filing of sequence listings".