This guidance provides clarity for test facilities on the expectations of national Good Laboratory Practice (GLP) compliance monitoring authorities on how test items are transported, received, identified, labelled, sampled, handled, stored, characterised, archived and disposed. The document consolidates existing OECD guidance on test items that are used in studies conducted in compliance with the Principles of GLP. It also aims to promote a consistent approach that is appropriate to the objective of the study and the nature of the test item.