Patients with haemophilia who develop inhibitors have unique treatment needs; bypassing agents such as Factor Eight Inhibitor Bypassing Activity, Anti-Inhibitor Coagulant Complex (FEIBA; Baxter AG, Vienna, Austria) are part of this therapeutic armamentarium. This study sought to increase comprehension of the full therapeutic profile of FEIBA by evaluating its safety and efficacy in the settings of acute bleeding, surgery, and prophylaxis. Information was collected through a postmarketing surveillance study; questionnaire booklets were distributed to 72 treatment centers in the United States and Europe. The booklets contained questions related to patient demographics, inhibitor titre determinations, and FEIBA treatment. Information comprising 200 FEIBA treatment periods and representing >4500 infusions was available for 63 patients with inhibitors (n = 60, haemophilia A; n = 3, haemophilia B). Twelve patients were in more than one treatment group. Efficacy was determined by a subjective global evaluation and was good or excellent in 82% of all acute, and 91% of all surgical, treatments. Additionally, prophylactic treatment resulted in improved or stabilised clinical orthopaedic status in 11 of 13 patients (85%). Based on available data, FEIBA was judged safe in all treatment situations by the small number of adverse events (<0.04%). No thrombotic complications occurred during any treatment episode. Results indicated that FEIBA was safe and effective in acute, surgical, and prophylactic treatment settings, supporting the utility of FEIBA as a treatment option for patients with inhibitors. However, prospective studies are advised.