PubMed IDs (a.k.a. PMIDs) seem to have been assigned sequentially:

However, some some PubMed IDs missing. I.e. https://www.ncbi.nlm.nih.gov/pubmed/2260 returns Error occurred: The following PMID is not available: 2260. Why are some PubMed IDs missing?

1 Answer 1


My background is databases in IT.

This is only a suggestion, but there are a few reasons why this behaviour is commonly observed

  • database IDs are commonly given out sequentially
  • it is possible that articles are submitted, but some reason are then removed by the submitter.
  • from time to time, data will be added erroneously by the system (duplicate data, incorrect data), and these IDs will be deleted.
  • as an efficiency aspect of databases, when a new ID is requested of the database it will usually give one greater than the highest ID.

This is not definitive on how Pubmed works, but it is very likely these are the reasons.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.