Traditionally, human histocompatibility testing (HLA) has been relegated to the narrow fields of bone marrow and solid organ transplantation. Consequently, basic information in the field has not been available to the wider laboratory medicine community. With the current interest in platelet typing and antibodies, HLA antibodies and severe respiratory problems, and the relationship of certain HLA genotypes to resistance or susceptibility to infectious diseases, there is a need for making general information on the HLA-system and its testing available to a much wider audience. This program will focus on presenting general principles of human histocompatibility testing in two parts: 1) the basic theory of the HLA system and typing, and 2) HLA antibody testing with current testing strategies. Lectures combined with case studies emphasize the use of HLA typing and antibody testing in transplantation and in transfusion medicine. There will be plenty of opportunity for questions.