Haemophilia A (factor VIII deficiency) is the most common type of haemophilia [1], affecting approximately 1 in 5000 males, although its prevalence varies globally [2] This letter presents a preplanned interim analysis of data collected up to September 1, 2012 for the guardian TM 2 extension trial. The primary objective is to assess the safety of turoctocog alfa for prevention and treatment of bleeds. The primary endpoint is the frequency of developing FVIII inhibitors. Key efficacy endpoints are haemostatic effect during treatment of bleeding, number of infusions needed to treat a bleeding episode and annualized bleeding rate (ABR).The guardian TM 2 extension trial enrolled 188 male patients [27 children (≤5 years), 28 children (6-11 years), 23 adolescents (12-17 years) and 110 adults (≥18 years)] with severe haemophilia A (FVIII level ≤1%) who had no history of FVIII inhibitors. The trial included 51 sites in 18 countries (Brazil,