Using an I.M.S. LifeLink dataset (19 September 2014-11 September 2015), we compared U.S. cardiologist prescribing of the reduced dose of apixaban (2.5 mg) or rivaroxaban (15 mg) to utilization in their corresponding nonvalvular atrial fibrillation registration randomized trials. Of all prescriptions written by cardiologists for these agents, 20.8% of apixaban and 21.7% of rivaroxaban prescriptions were for a reduced dose; corresponding to a 4.4-fold (16.1% absolute) increase in the use of reduced dose apixaban and a 3% relative (0.6% absolute) increase in reduced dose rivaroxaban use vs. their respective registration trials. Further research is needed to better understand appropriate dosing of patients with novel anticoagulants.