Compared to Vitamin K antagonists (VKA), novel oral anticoagulants (NOACs) appear to be safer in terms of major bleeding risks with added advantage of having fixed dosing schedules when used in patients with non-valvular atrial fibrillation (AF). We sought to study the differences as sources and severity of anticoagulant-associated haemorrhage in patients with AF in the year preceding introduction of NOACs (first cohort) as compared to post approval of the NOACs (second cohort) by retrospectively reviewing the hospital admissions, as well as the pharmacodynamic and pharmacokinetic interactions between time periods. There were 359 patients for the first cohort and 405 patients for the second cohort, including 57 patients prescribed NOACs. There was no significant difference in age, deaths, source of bleeding, or rate of pharmacokinetic or pharmacodynamic interaction between the two time periods. Comparing all VKA patients to patients prescribed NOAC's, there were non-significant but higher rates of intracerebral bleed, significantly higher rates of pharmacokinetic (194 (25.4%) versus 0 (0%), p