The peer review process can lead to changes in the interpretation of the slides and the reported results, and potentially the outcome and conclusions of the study. The purpose of this document is to provide guidance to pathologists, test facility management, study directors and quality assurance personnel on how the peer review of histopathology should be planned, managed, documented and reported in order to meet GLP expectations and requirements. This document is a complement to the guidance provided in section 3.6.3.7 of OECD Guidance Document 116 (series on testing and assessment), whose focus is on how histopathology peer review should be conducted.