This past Tuesday, ISI Thomson released the official 2007 Impact factor (IF) numbers for over 6,000 journals.  Retrovirology’s 2007 IF number is 4.04.  Out of 6,000 journals in the ISI data base, this places Retrovirology at number 555.  However, a better comparison would be to rank Retrovirology with virology journals that primarily publish basic virus research articles.  If such a comparison is made, then Retrovirology would rank right below Journal of Virology and above many other excellent and well established journals like Virology.  Please note that in the list below, only Retrovirology is an Open Access journal.  This means that, different from an article published in the other journals, a Retrovirology paper is immediately available in full text form for all to read online, unencumbered by subscription fees.