Major bleeding is a serious and potentially fatal complication of treatment with vitamin K antagonists (VKAs). Prothrombin complex concentrates (PCCs) can substantially shorten the time needed to reverse VKA effects. To determine the efficacy and safety of 3-factor PCCs for the rapid reversal of VKAs in patients with major bleeding. Patients receiving VKAs and suffering from acute major bleeding were eligible for this prospective cohort study if their international normalized ratio (INR) was higher than or equal to 2.0. Stratified 35-50 IU kg(-1) PCC doses were infused based on initial INR. A total of 126 patients (62 males; mean age: 74 years, range 37-96 years) were enrolled. The mean INR at presentation was 3.3 (range 2-11). At 30 min after PCC administration the mean INR was 1.4 (range: 0.9-3.1), declining to less than or equal to 1.5 in 75 % of patients. The benefit of PCC was maintained for a long time, since in 97 % of all post-infusion time points through 96 h the mean INR remained lower than or equal to 1.5 (mean: 1.19; range: 0.9-2.3). During hospitalization neither thrombotic complications nor significant adverse events were observed and 12 patients died (10 %); none of the deaths was judged to be related to PCC administration. 3-factor PCC administration is an effective, rapid ad safe treatment for the urgent reversal of VKAs in patients with acute major bleeding. Broader use of PCC in this clinical setting appears to be appropriate.