Professor McMahon is Director of the Department of Renal Medicine and Obstetric Medicine at Eastern Health, and Professor of Nephrology at Monash University.
Before this he was at the Western and Royal Melbourne Hospitals for 15 years, after a 2-year post-doctoral fellowship in Oxford, England. He is the Immediate Past-President of the Society of Obstetric Medicine of Australia and New Zealand.
He is, and has been, a member of various editorial boards and committees, including Chair of the Victorian Renal Health Clinical Network Dialysis Sub-Committee, and a member of the Renal Health Clinical Network Leadership Group. He has been an associate editor of Nephrology, Dialysis and Transplantation, and continues to review numerous international journals. He is involved in several international and national research studies and maintains an active interest in teaching, primarily through his role as Senior National Examiner for the Royal Australasian College of Physicians. He also maintains an active interest in clinical medicine, and clinical and laboratory-based research, with over 100 peer-reviewed publications.