Dr Aw was trained in internal medicine at Singapore General Hospital and Kings College Hospital & Medical School, London, U.K. He was faculty member of the National University of Singapore (NUS) medical school from 1980-2006 and rose to the rank of full Professor (Pathology). He underwent further training in clinical chemistry at the Department of Pathology & Lab Medicine, Hospital of the University of Pennsylvania, Philadelphia, USA from 2001-2004. He was responsible for setting up the Chemical Pathology services at the new National University Hospital (NUH), which opened in 1985. Thereafter he served as the inaugural chief of the Department of Laboratory Medicine from 1988-2002. He was Vice-Dean of the NUS medical school from 1994-2002. From 1995-2000 he assumed additional responsibilities as Medical Director of the NUS Alexandra campus Hospital (AH).At NUH he introduced many process improvement initiatives
Under his leadership, NUH and AH were the first two hospital labs in the Asia-Pacific to be accredited by the College of American Pathologists (CAP) in 1984 and 1988. At NUH he was consultant physician to the Endocrine and Cardiology clinics. He joined Changi General Hospital (CGH) in 2006 and started several Lean initiatives that have enabled CGH to attain and maintain good turnaround times (less than 1 hour) for many of the common tests that doctors require. CGH was accredited by CAP in 2007. He attends to patients at the Internal Medicine clinic at Raffles Hospital since 2006.
Dr Aw has held part-time academic appointments at the Monash Medical school from 2006-2010 - Professor (Chemical Pathology), Malaysia campus and honorary Professor (Medicine), Clayton campus. Professor Aw is medical director (part-time) of ICON Central Laboratories Singapore since 2008. ICON Labs obtained CAP accreditation in 2008. Professor Aw has published widely and delivered over 300 lectures in over 23 countries on Health policy and Lab Medicine.