After a dalliance with chemistry, Len Harrison graduated in medicine from the University of New South Wales last century before most people were born. He specialized in endocrinology and diabetes, researched insulin receptor expression-regulation in human cells and then did a post-doc with Jesse Roth and Ron Kahn at the NIH. He returned to the Royal Melbourne Hospital to a clinical endocrine position but was eventually rescued by Gus Nossal and moved to WEHI. This entailed becoming an immunologist. He headed the Autoimmunity and Transplantation Division in WEHI and the Immunology and Allergy Department in the hospital 1987-2010. Currently, he is a Senior Principal Research Fellow, NHMRC, and Professor, Molecular Medicine Division, WEHI. His major research interests are immune regulation and immune therapies, applied to type 1 diabetes. His research awards include C.J. Martin Fellowship, Wellcome Australia Medal, Susman Prize (RACP), Kellion Medal (Australian Diabetes Society) and Rumbough Award for Scientific Excellence (JDRF). Len was a Director of the Australian Society for Medical Research, President of the Australian Diabetes Society and President of the Immunology of Diabetes Society, and remains on too many committees.