Associate Professor William Sewell is Chief Examiner in Immunopathology for the Royal College of Pathologists of Australasia. He graduated in Medicine from Sydney University in 1978. After research work in Australia and the UK, he completed his pathology training in 1993 at St Vincent’s Hospital. He has special expertise in the diagnostic applications of flow cytometry, in particular in the analysis of leukaemia and lymphoma, and he is Vice-President of the Australasian Flow Cytometry Group. He is appointed to the Faculty of Medicine at the University of New South Wales, where he teaches immunology and pathology to medical students. He conducts research into the role of the immune system in allergy.