In order to update the review published in Tissue Antigens in 1997, we present here a new overview on microsatellites in the HLA region, including additional information, with focus on the following points: Description of 103 microsatellite characteristics in the HLA region, 50 markers having been newly described since 1996. An integrated map of the HLA region, including microsatellites and some HLA genes, revealing an important microsatellite density in the MHC (Class I, Class II and Class III regions). A synthesis of microsatellite analysis in disease studies, summarizing results of microsatellite approaches in 24 pathologies, including autoimmune diseases, HLA-associated or HLA-linked diseases and cancers. Other applications of HLA region microsatellites in population or transplantation studies. As tandem repeats, especially microsatellites, continue to be characterized in the HLA region and used for various applications, an updated overview of literature and molecular database information on this topic is presented, with reference to Foissac et al. (1). The literature review and molecular information presented in the Whitehead database (WDB) (http://www-genome.wi.mit.edu/) until June 1998 are taken into account, in addition to previous information, resulting in an analysis of HLA region microsatellite investigation for the period 1993-1998.