Guy is a respiratory physician and respiratory and environmental epidemiologist with interests in tuberculosis, chronic airways disease and air pollution. He is Scientia Professor at UNSW Sydney and NHMRC Senior Principal Research Fellow. He is currently President of the International Union Against Tuberculosis and Lung Disease and, until recently, was co-Editor-in-Chief of the International Journal Against Tuberculosis and Lung Disease. He is a Chief Investigator in the Australian NHMRC-funded Centre for Research Excellence on Tuberculosis. He has a long-standing, close and active collaboration with the National Tuberculosis Program in Vietnam, and with colleagues in that country, has conducted a number of projects, including cluster randomised controlled trials, investigating interventions for better control of TB in high burden settings.