MPEP 1823
The Description

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

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1823    The Description [R-07.2022]

PCT Article 5

The Description

The description shall disclose the invention in a manner sufficiently clear and complete for the invention to be carried out by a person skilled in the art.

PCT Rule 5

The Description.

5.1 Manner of the Description

  • (a) The description shall first state the title of the invention as appearing in the request and shall:
    • (i) specify the technical field to which the invention relates;
    • (ii) indicate the background art which, as far as known to the applicant, can be regarded as useful for the understanding, searching and examination of the invention, and, preferably, cite the documents reflecting such art;
    • (iii) disclose the invention, as claimed, in such terms that the technical problem (even if not expressly stated as such) and its solution can be understood, and state the advantageous effects, if any, of the invention with reference to the background art;
    • (iv) briefly describe the figures in the drawings, if any;
    • (v) set forth at least the best mode contemplated by the applicant for carrying out the invention claimed; this shall be done in terms of examples, where appropriate, and with reference to the drawings, if any; where the national law of the designated State does not require the description of the best mode but is satisfied with the description of any mode (whether it is the best contemplated or not), failure to describe the best mode contemplated shall have no effect in that State;
    • (vi) indicate explicitly, when it is not obvious from the description or nature of the invention, the way in which the invention is capable of exploitation in industry and the way in which it can be made and used, or, if it can only be used, the way in which it can be used; the term "industry" is to be understood in its broadest sense as in the Paris Convention for the Protection of Industrial Property.
  • (b) The manner and order specified in paragraph (a) shall be followed except when, because of the nature of the invention, a different manner or a different order would result in a better understanding and a more economic presentation.
  • (c) Subject to the provisions of paragraph (b), each of the parts referred to in paragraph (a) shall preferably be preceded by an appropriate heading as suggested in the Administrative Instructions.


PCT Administrative Instructions Section 204

Headings of the Parts of the Description

  • (a) The headings of the parts of the description should be as follows:
    • (i) for matter referred to in Rule 5.1(a)(i), "Technical Field";
    • (ii) for matter referred to in Rule 5.1(a)(ii), "Background Art";
    • (iii) for matter referred to in Rule 5.1(a)(iii), "Disclosure of Invention" or "Summary of Invention";
    • (iv) for matter referred to in Rule 5.1(a)(iv), "Brief Description of Drawings";
    • (v) for matter referred to in Rule 5.1(a)(v), "Best Mode for Carrying out the Invention," or, where appropriate, "Mode(s) for Carrying out the Invention" or "Description of Embodiments;
    • (vi) for matter referred to in Rule 5.1(a)(vi), "Industrial Applicability";
    • (vii) [Deleted]
    • (viii) [Deleted]
  • (b) The heading "Title of Invention" shall preferably precede the title of the invention.


PCT Administrative Instructions Section 209

Indications as to Deposited Biological Material on a Separate Sheet

  • (a) To the extent that any indication with respect to deposited biological material is not contained in the description, it may be given on a separate sheet. Where any such indication is so given, it shall preferably be on Form PCT/RO/134 and, if furnished at the time of filing, the said Form shall, subject to paragraph (b), preferably be attached to the request and referred to in the check list referred to in Rule 3.3(a)(ii).
  • (b) For the purposes of designated Offices, which have so notified the International Bureau under Rule 13 bis.7(a), paragraph (a) applies only if the said Form or sheet is included as one of the sheets of the description of the international application at the time of filing.

37 C.F.R. 1.435  The description.

  • (a) The application must meet the requirements as to the content and form of the description set forth in PCT Rules 5, 9, 10, and 11 and sections 204 and 208 of the Administrative Instructions.
  • (b) In international applications designating the United States the description must contain upon filing an indication of the best mode contemplated by the inventor for carrying out the claimed invention.

The description must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. It must start with the title of the invention as appearing in Box No. I of the request. PCT Rule 5 contains detailed requirements as to the manner and order of the description, which, generally, should be in six parts. Those parts should have the following headings: "Technical Field," "Background Art," "Disclosure of Invention," "Brief Description of Drawings," "Best Mode for Carrying Out the Invention" or, where appropriate, "Mode(s) for Carrying Out the Invention," and "Industrial Applicability," where applicable.

For international applications having an international filing date before July 1, 2022, headings for "Sequence Listing" and "Sequence Listing Free Text" should also be used where applicable.

The details required for the disclosure of the invention so that it can be carried out by a person skilled in the art depend on the practice of the national Offices. It is therefore recommended that due account be taken of national practice in the United States of America when the description is drafted. The need to amend the description during the national phase may thus be avoided.

This applies likewise to the need to indicate the "best mode for carrying out the invention." If at least one of the designated Offices requires the indication of the best mode (for instance, the United States Patent and Trademark Office), that best mode must be indicated in the description.

A description drafted with due regard to what is said in these provisions will be accepted by all the designated Offices. It might require more care than the drafting of a national patent application, but certainly much less effort than the drafting of multiple applications, which is necessary where the PCT route is not used for filing in several countries.