Probably 90% of the estimated 14-15 million people living with HIV infection worldwide reside in developing countries. With the global HIV pandemic disproportionately affecting people in the developing world developing countries need to be involved in all stages of vaccine development from initial research to the approval and licensing of a product to the public. During 1991 World Health Organization (WHO) teams visited 14 developing countries in Africa Asia and Latin America to assess their capacity and interest in conducting HIV vaccine trials. The assessments considered the epidemiological aspects of the epidemic in the country the clinical and laboratory infrastructures available the logistical and operational aspects of conducting vaccine-related research and the community and political support for HIV vaccine trials. In 1992 the WHO Steering Committee on Vaccine Development announced that it would work with the national authorities and scientists of Brazil Rwanda Thailand and Uganda to develop and implement comprehensive plans for HIV vaccine research development and evaluation. The activities in Rwanda however were suspended due to recent genocide and related civil unrest. National plans have been developed with WHO assistance in the other three countries. HIV isolation and characterization and epidemiologic clinical and social and behavioral studies are discussed as essential for the preparation of the field sites for vaccine trials.