Despite its shortcomings, peer review is still the best tool of scientific publishing. It brings benefits not only to the journal and its authors, but to the peer reviewers: they are privileged to have an insight into the latest research and still unpublished results in their scientific field. Reviewers also build up their ability to critically assess scientific papers, which may be useful in their own professional work and development. We wrote these brief guidelines to help the reviewers for the Croatian Medical Journal learn about the specificities of the journal and editor's expectations from their partnership with peer reviewers. The guidelines were created primarily for new reviewers, but they may be useful as a refresher text for experienced reviewers.