In accordance with Directive 2010/63/EU, the principle of the 3Rs (Replacement, Reduction and Refinement) needs to be considered when selecting approaches for validating quality control tests in laboratories for regulatory testing of human and veterinary medicinal products. Collaborative studies between laboratories may be carried out to introduce new 3Rs methods for regulatory purposes where animal tests have been traditionally used. This guidance aims to facilitate transfer of the new methods validated in such trials with a view to implementing 3Rs for testing in a product specific context in laboratories originally involved in the collaborative trial or in new laboratories.