Professor Emeritus Gary Halliday serves in the Sydney Medical School at the University of Sydney, where he holds the position of Professor within the Discipline of Dermatology. He is affiliated with the Bosch Institute and the Sydney Cancer Centre. Halliday earned his PhD in immunology from Monash University in 1981 and received his Doctor of Science from the University of Sydney in 2001. Throughout his career, he has focused on the immunological consequences of ultraviolet radiation exposure on the skin, elucidating mechanisms of UV-induced immunosuppression that contribute to skin carcinogenesis. His investigations have explored how UVA and UVB radiation inhibit effector and memory T-cell responses, promote nitric oxide release from keratinocytes, and induce DNA damage, while also examining protective strategies such as sunscreens, vitamin E, and nicotinamide.

Halliday's prolific research output includes over 270 peer-reviewed publications, garnering more than 13,000 citations. Key works encompass studies on the suppressive effects of ultraviolet radiation on skin immunity published in 2012, the role of nicotinamide in enhancing DNA repair and preventing non-melanoma skin cancers as detailed in a 2015 New England Journal of Medicine phase 3 trial, and reviews on nicotinamide for photoprotection in 2019. He has advanced understanding of chromatin structure changes following UV damage, BRM's inhibition of keratinocyte proliferation, and UVA's contributions to mutations in epidermal p53. As former President of the Australasian Society for Dermatology Research and a notable university member honored in 2018, Halliday has shaped the field through leadership, mentorship of numerous PhD students, and contributions to international photobiology committees. His findings have informed clinical approaches to skin cancer prevention and treatment.

Professional Email: gary.halliday@sydney.edu.au