Polypharmacy is increasing among older Australians, raising their risk of experiencing medication-related harm. As part of the prescribing continuum, deprescribing is a strategy proposed to reduce inappropriate polypharmacy. This study explored factors that influence deprescribing among Australian GPs using a new 21-item survey to measure GP attitudes and practices. The 85 GP responses indicated that many factors are supportive of deprescribing. GPs suggest that they are willing to explore their older patients' deprescribing preferences; they believe that they have enough information about the potential harms and benefits of medication to inform their deprescribing decisions and are confident to communicate this information to their patients. GPs did not consider their patients would interpret deprescribing as being 'given up on'. Limited time to review medications, poor communication between prescribers and a perception that other prescribers do not respect their role as overall coordinators of their older patients' medications were considered by respondents to be unsupportive of deprescribing. Overall, despite GPs reporting many supportive factors for deprescribing, the influence of unsupportive factors appears to remain strong, as deprescribing is not routinely considered in practice.