Background Co-prescribing a proton pump inhibitor (PPI) with an anticoagulant, in patients with atrial fibrillation (AF) at high risk of bleeding, decreases the risk of gastrointestinal bleeding. This study aimed to identify Australian prescribing trends for this topic to inform practice in this area. Methods This was a retrospective cohort study in which a cross-sectional analysis of general practice data obtained from MedicineInsight was performed, to evaluate current Australian prescribing trends of PPIs in patients with AF. Patients aged 18 years or more initiated on an oral anticoagulant between January 1st, 2011 and April 25th, 2019 were included. Results A total of 28,863 participants were included; of these, 5,092 (17.6%) received PPI co-therapy. There were 4,211 (14.6%) participants at high risk of bleeding, with 878 (20.9%) of these receiving PPI co-therapy. Participants were significantly more likely to be prescribed a PPI if prescribed dabigatran (adjusted odds ratio (AOR) 1.42 [1.28-1.57], 95% confidence interval (CI)), apixaban (AOR 1.36 [1.26-1.46], 95%CI) or rivaroxaban (AOR 1.28 [1.18-1.38], 95%CI) compared to warfarin. Factors associated with PPI prescribing included, antiplatelet co-therapy (AOR 2.09 [1.82-2.39], 95% CI), high CHA2DS2-VASc score (≥2 male or ≥3 female) (AOR 1.50 [1.28-1.77], 95% CI) and a low ORBIT score (<3) (AOR 1.42 [1.23-1.64], 95% CI). Conclusion In this large nationally representative cohort, only 20.9% of participants who were at high risk of bleeding were co-prescribed a PPI. Further research is required to investigate whether increased prescribing of PPIs could improve patient outcomes. Key words: Atrial fibrillation, proton pump inhibitors