Turoctocog alfa is an approved B-domain truncated recombinant factor VIII concentrate for adults and children with haemophilia A. Clinical data for turoctocog alfa have been reported from the guardian™1, guardian™2 and guardian™3 phase III trials. guardian™1 and guardian™3 phase III trials enrolled 150 adolescents/adults (≥12 yr), and 63 children (<12 yr), respectively, with previously treated severe haemophilia A and no history of inhibitors; 188 of these patients continued into the ongoing guardian™2 extension trial. In the three trials, patients have received prophylaxis with turoctocog alfa three times weekly or every second day, with breakthrough bleeds resolved to an expected postinjection level of ≥0.50 IU/mL. No safety concerns have arisen, and no patients have developed confirmed inhibitors (primary endpoint). Indeed, no confirmed inhibitors have been detected in >200 patients treated for a cumulative total of >54 000 exposure days in the phase III trials. Pooled efficacy data show a favourable long-term effect of turoctocog alfa on annualised bleeding rate and a success rate for haemostatic response of 86%; 90% of bleeds were resolved with 1–2 doses. This article reviews the clinical development of turoctocog alfa with reference to the guardian™ clinical programme, describing results obtained to date and ongoing trials.