Ruff is an associate professor at the Nossal Institute for Global Health, University of Melbourne. He is also on the Australian Board of the International Campaign to Abolish Nuclear Weapons (ICAN), the 2017 Nobel Peace Laureate and has written extensively on nuclear issues, including the hazards or ionizing radiation, nuclear weapons, nuclear war and nuclear famine.
He serves as medical advisor to the international department of Australian Red Cross and is a member of the World Health Organization Western Pacific Region's Hepatitis B Expert Resource Panel. Ruff has previously led the development of travel medicines, worked on the control of Hepatitis B and worked to improve maternal and child health in Indonesia and the Pacific islands. He has also worked as a regional medical director for vaccines, employed by a major manufacturer.
Ruff has been an active member of the Medical Association for Prevention of War in Australia for over three decades and is a co-president of International Physicians for the Prevention of Nuclear War (IPPNW). He helped establish the International Campaign to Abolish Nuclear Weapons (ICAN) and was its founding chair. He remains a member of the ICAN Australia Committee and ICAN's International Steering Group. In 2010, he told the Sydney Morning Herald: "We've come a long way. The numbers of nuclear weapons have been reduced from the peak of 70,000 in 1986 to about 23,000 - that's a drastic reduction."
Ruff co-authored an article with former Australian Prime Minister Malcolm Fraser entitled "2015 is the year to ban nuclear weapons." In 2017, Ruff expressed his pride at the work of ICAN and its receipt of the 2017 Nobel Peace Prize for “its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons”.
In 2012, Ruff was appointed a Member of the Order of Australia “for service to the promotion of peace as an advocate for the abolition of nuclear weapons, and to public health through the promotion of immunisation programs in the South-East Asia – Pacific region”. In October 2017 ICAN was awarded the Nobel Peace Prize. Ruff was appointed an Officer of the Order of Australia (AO) in the 2019 Queen's Birthday Honours for "distinguished service to the global community as an advocate for nuclear non-proliferation and disarmament, and to medicine".
Ruff was born in Adelaide, South Australia in 1955. He is married to Charlotte and the couple have two adult children, Ingrid and Kristian. He has described becoming a parent as strengthening his resolve and commitment to advocating for nuclear disarmament. Ruff is a graduate of Monash University and Glen Waverley Secondary College.