It is twenty years and nine workshops on from the first international gathering of tissue typers in Durham, North Carolina. The size and range of the series of meetings centred on this year's workshop show the success achieved by the unique collaboration of workers in the HLA field. The main workshop meeting in Munich, organized by Ekkehard Albert and Wolfgang Mayr, was preceded by the third H-2 and HLA cloning meeting, organized by Jean Dausset in Strasbourg and by a biochemistry workshop in Munich organized by Julia and Walter Bodmer and Michael Crumpton. The workshop was then followed by a conference in Vienna which demonstrated, by the selection of papers presented, the increasing importance of molecular and biochemical studies in the understanding of the HLA region of chromosome 6, its function and relationship to disease.