Considerable scientific and political interest has been expressed, parallelling public concern about the effects of chemicals on the immune system and the implications of those effects for health. Coupled with speculation about the magnitude and extent of the problem is discussion of needs for predictive testing and regulatory control measures. The first international seminar on the immunological system as a target for toxic damage was held in Luxembourg in 1984. It was organized by the International Programme on Chemical Safety (United Nations Environment Programme-International Labour Office­ World Health Organization) and the Commission of the European Communities with the support of the US Environmental Protection Agency and the National Institute of Environmental Health Sciences (USA) and the participation of the International Society of Immunopharmacology. In view of the perceived importance of imrnunotoxicity, it was considered necessary to organize a follow-up meeting. Thus, an international workshop on the immunotoxicity of metals and immuno­ toxicology was held in Hanover, Federal Republic of Germany, on 6-10 November 1989.