PubMed Commons, a new feature of PubMed which allows commenting on articles, is now live. All authors of publications cited in PubMed are eligible to participate. They can comment on any article in PubMed, rate the helpfulness of comments, and invite other authors cited in PubMed to join. Links to other articles can be embedded in the comments, using a PubMed ID number. You can also set up alerts for articles with comments using your MyNCBI account. Those who are not authors can still view the comments on articles, and there is a new filter available called Reader Comments, which can be applied to search results. It’s also possible to view all the comments in PubMed (433 at this writing): Find all PubMed Citations with comments. We hope that PubMed Commons will lead to open communication and enhance the scholarly record. To participate, see How to Join PubMed Commons. Follow PubMed Commons on Twitter here, and read the PubMed Commons blog for additional information.