There are moral, legal, social and economic reasons for implementing humane endpoints in areas of animal experimentation where animal wellbeing may be seriously compromised. In 1998 the 1st International Conference on Humane Endpoints was held in Zeist (NL) to discuss the possibilities and opportunities for implementation of humane endpoints. During the conference, important issues relating to the recognition and assessment of adverse effects in animals, and the determination, validation and acceptance of humane endpoints were addressed. The purpose of the second conference on Humane Endpoints will be to review the progress made in this field and to discuss new developments. Important issues relating to the recognition and assessment of adverse effects in animals and the determination, validation, implementation and acceptance of humane endpoints will be addressed. New techniques, new approaches and new strategies using non-invasive methods will be presented. The training of observers and the use of recently developed remote sensing devices will be other key issues. This conference is aimed at those with responsibility for the use, care and welfare of research animals such as regulators, scientists, veterinarians, technicians, animal welfarists and members of ethics committees.