These recommendations are primarily intended to standardize health monitoring programmes and reporting. In this way they may also help to standardize the microbiological quality of animals. However, it is not a requirement of these recommendations that animals tested are free from all of the microorganisms listed. Health monitoring is a complex issue. Therefore, it is recommended that a person with suf® cient understanding of the principles of health monitoring (FELASA Category D, Nevalainen et al. 1999) be identi® ed as the individual responsible for devising and maintaining a health monitoring policy for the facility. It should be noted that health monitoring is not con® ned to laboratory reporting. There should also be engendered a culture of communication between animal technicians, facility managers, veterinarians and researchers so that observed abnormalities in breeding animals and experimental data can rapidly be evaluated and appropriate action taken.