Summary. Factor VIII (FVIII) concentrates have revolutionized the treatment of patients with haemophilia A. Concerns over the transmission of viral infections through these products have been addressed through stringent, donor-screening procedures and robust antiviral manufacturing steps. Bio Products Laboratory has developed a high-purity FVIII product with von Willebrand factor, Optivate®. Its safety, tolerability and efficacy as prophylaxis and treatment of bleeds have been established in long-term studies. Seventy previously treated patients with severe haemophilia A, with ≥20 exposure days, were recruited into two long-term, multicentre, open-label studies. The protocols were virtually identical. Patients received Optivate® either prophylactically or on-demand. A mean of 159.0 EDs were experienced over 11 320 infusions. Under both conditions, Optivate® was well tolerated. Only 10% of patients experienced a treatment-related adverse event; the most commonly reported were headache (4% of patients) and dizziness (3% of patients). The mean number of bleeds/patient over the 2 year treatment period was 23.5 during prophylactic use and 70.4 during on-demand use. In patients treated prophylactically, clinical responses to breakthrough bleeds were rated by physicians as excellent or good and as very helpful or helpful by patients in 95% of bleeds. Clinical responses for on-demand patients were rated as excellent or good by physicians and helpful or very helpful by the patients for 91% of bleeds. There were no viral transmissions or inhibitors. The studies confirm the clinical efficacy and safety of Optivate® in both prophylactic and on-demand management of patients with haemophilia A.