Factor XI (FXI) deficiency is associated with bleeding after invasive procedures. Risks of human plasma-derived FXI replacement products include transfusion transmitted infection, thrombosis and fluid overload. This study was designed to test the hypothesis that recombinant factor VIIa (rFVIIa) is an effective haemostatic agent in patients with FXI deficiency undergoing surgery. Fourteen FXI deficient patients [five severely deficient (FXI:C <20 U dL(-1)) and nine partially deficient (FXI:C 20-70 U dL(-1)] received rFVIIa to prevent surgical bleeding during five major, four minor and six dental procedures. Minor surgical and dental procedures were covered with two doses of rFVIIa (90 microg kg(-1) i.v.), the first pre-operatively and the second 4 h postoperatively. Major surgery was covered with 90 microg kg(-1) i.v. two hourly for the first 24 h and four hourly for the second 24 h. Oral tranexamic acid was given for 7 days postoperatively. Effective haemostasis was observed in all cases and no alternative haemostatic agents or blood transfusions were required. Three adverse events were recorded; an acute cerebrovascular accident in a patient with a history of cardiovascular disease, an allergic reaction and local phlebitis. In this study, rFVIIa was an effective alternative to plasma-derived FXI replacement for the prevention of surgical bleeding in FXI deficient patients but rFVIIa may not be suitable for patients with pre-existing risk factors for thrombosis.