Basic question (though I haven't found it here):

How do I comment out parts (some lines within an entry which I would like to save for later) of a BibTex file?

Apparently, @ can be used to comment out lines (but not be used within a comment itself), but only outside an entry, you have to move the commented lines out of the entry they belong to). Is there any other way?


2 Answers 2


You can "comment" whole entries by erasing the @ in front of the type declaration (@book -> book); there are no other ways of commenting parts of entries. However, unknown fields are ignored, so you can say


in order to ignore the pages field. Also repeated fields are ignored.

As a matter of fact, text between entries will be ignored, which is why the above works; only what appears between the braces like in


is considered. However, it should be noted that Biber is stricter than BibTeX in this respect, so it will warn about what it considers junk between entries. Adding a % at the beginning of a line turns off Biber's warnings.

  • 47
    Good. Now '//' before a line is treated as commented out.
    – Peng Zhang
    Commented Jan 23, 2014 at 21:03
  • 4
    For me, using // with TeXstudio and biber puts it into a never ending compile loop. However, I can put % before a line and it won't appear in the bibliography, see this answer, but unfortunately TeXstudio's color highlighting won't make it grey out like a comment. Commented Sep 3, 2016 at 0:50

Emacs uses the prefix '@Comment' when using the "comment-or-uncomment-region" command in a BibTex file. This works on any line (at least in my version).

Using '%' also works for me, but I remember having it not work once -- I guess it may not be the most compatible.

Otherwise, you can achieve a similar effect to commenting out by changing the strings: (1) Change the key of a whole bibtex entry to something else, or (2) change the name of a BibTex field, as BibTex ignores field it doesn't know. In particular, I often "comment out" fields by prepending an underscore to the field name, e.g., I include

_pages = { TODO },

to mark that I should add the page number later.

  • 2
    Yeah, I put "comments" with % in bibtex in Overleaf, and they were coloured gray. However, I started getting errors from "commented out entries". So % - comments work great outside entries. Commented Mar 28, 2020 at 9:53
  • I have done something like this - @article{.... year = "2018", Comment ="not important- you can delete this citation"}
    – PoreyS
    Commented Aug 2, 2022 at 19:26

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