Denis CBE FRS FRCP developed the first viable mathematical model of the heart cell in 1960 and is a pioneer of ‘Systems Biology’. His research focuses on using computer models of biological organs and organ systems to interpret function from the molecular level to the whole organism. Together with international collaborators, his team has used supercomputers to create the first virtual organ, the virtual heart. He held the Burdon Sanderson Chair of Cardiovascular Physiology at Oxford University from 1984 to 2004 and is currently Professor Emeritus and co-Director of Computational Physiology. As Secretary General of the International Union of Physiological Sciences 1993-2001, he played a major role in launching the Physiome Project, an international project to use computer simulations to create the quantitative physiological models necessary to interpret the genome, and he was elected President of the IUPS at its world congress in Kyoto in 2009.