An expert Working Group was set up in December 2000 to develop recommendations for users and industry on the evaluation of proper function and operation of individually ventilated cage (IVC) systems. The full report of their recommendations is in two parts--'Part 1: Test Instructions' and 'Part 2: Evaluation Criteria'--both of which have been published in full on the Laboratory Animals Ltd website. They can be found at http://www.lal.org.uk/IVC/index.html. Evaluation of and feedback on the recommendations to further refine their use and scientific basis is encouraged. This Summary Report provides a brief overview of the background to the development of the full report and the issues it addresses.