This document specifies the minimum requirements to be satisfied to ensure and demonstrate that proper provision has been made to minimize pain and distress, which can negatively affect the validity of the data. This document is for those who commission, design and perform testing or evaluate the data to assess the biocompatibility of materials intended for use in medical devices, or that of the medical devices themselves. This document makes recommendations and offers guidance intended to facilitate further reductions in the overall number of animals used, refinement of test methods to reduce or eliminate pain or distress in animals, and the replacement of animal tests by other scientifically valid means not requiring animal tests. This document applies to tests performed on living vertebrate animals, other than man, to establish the biocompatibility of materials or medical devices. This document does not apply to tests performed on invertebrate animals and other lower forms; nor (other than with respect to provisions relating to species, source, health status, and care and accommodation) does it apply to testing performed on isolated tissues and organs taken from vertebrate animals that have been euthanized.