The audio conference will be presented in three parts. In the first section, an introduction to the HLA system - its genetics, structure, function and nomenclature-will be provided. In the second part of the audio conference, methods commonly used in HLA laboratories will be described and their sensitivity, complexity, cost and uses will be compared. In the final section, blood bank applications of HLA will be discussed, including investigation of platelet refractoriness, selection of HLA matched platelets, investigation of suspected TRALI and the investigation of transfusion related graft vs host disease.