Turoctocog alfa pegol (ESPEROCT^®; N8-GP; Novo Nordisk A/S, Bagsvaerd, Denmark) is an extended half-life recombinant factor VIII (FVIII) shown to be efficacious for the prevention and treatment of bleeding episodes in patients with hemophilia A. Post-administration monitoring of patients on factor replacement products may be necessary during the course of treatment. However, many reagents currently available in Japan for the measurement of FVIII activity have never been tested for accuracy when measuring turoctocog alfa pegol. Here, we evaluated FVIII activity measurements of hemophilia A plasma spiked with turoctocog alfa pegol using both the ACL TOP^® 550 and CS-5100 coagulation analyzers and activated partial thromboplastin time (aPTT) reagents, a chromogenic kit and calibrators specific to Japan. Ten of 13 aPTT reagents and the chromogenic kit (Revohem^TM FVIII Chromogenic [Sysmex, Kobe, Japan]) recovered turoctocog alfa pegol within ±30% of target concentration. Three aPTT reagents that use silica as a contact activator underestimated turoctocog alfa pegol recovery in spiked samples and therefore should not be used to measure FVIII activity in patients treated with turoctocog alfa pegol. Overall, turoctocog alfa pegol can be accurately measured with reagents and kits available in and widely used throughout Japan.