Background: Haemorrhage remains a leading cause of morbidity and mortality in trauma patients. Fibrinogen is an essential endogenous component of haemostasis and the plasma level is associated with bleeding, transfusion and outcome. Fibrinogen concentrate is widely used to correct acquired hypofibrinogenaemia, recommended by several international guidelines for the treatment of trauma patients, but evidence is lacking regarding the treatment safety and efficacy.We aim to assess the efficacy and safety of an immediate pre-emptive first-line treatment with fibrinogen concentrate in patients with trauma haemorrhage in need of haemostatic resuscitation. Methods/Design: This is a single-centre, randomized (1:1, active:placebo), placebo-controlled, double-blinded, investigator-initiated phase II trial. The trial population consists of 40 adult patients (>18 years) with traumatic, critical bleeding admitted to the Level 1 Trauma Centre at Rigshospitalet in Copenhagen, with immediate need for blood transfusion on arrival and an expected need for haemostatic resuscitation with multiple transfusions during the initial resuscitation. Patients will receive either pre-emptive administration of a bolus dose of 60–70 mg/kg fibrinogen concentrate (Riastap®) or placebo 0.9 % saline in equal volume to active treatment, both given as intravenous infusion blinded for the person administering the infusion.The primary end point is the change in thrombelastograph (TEG®) functional fibrinogen maximum amplitude in millimetres at 15 min after the intervention. The follow-up period on safety events and mortality will be until day 30.To detect a difference in the change from baseline to the 15-minute post-randomization measurement of 6–8 mm in TEG® functional fibrinogen maximum amplitude with a power of 0.90 and alpha of 0.05, we require 19 patients in each group. We have chosen to include 40 patients, 20 evaluable patients in each randomization group in case of attrition, in the present trial. Discussion: Patients considered to be included in the trial will temporarily have a compromised consciousness because of the acute, critical bleeding related to trauma, so scientific guardians will co-sign the informed consent form. Next of kin and the patients’ general practitioner or the patients will co-sign as soon as possible.This trial will test whether immediate pre-emptive fibrinogen concentrate administered to adult trauma patients as first-line treatment of trauma haemorrhage will increase the clot strength as evaluated by thrombelastography, transfusion requirements and survival in patients receiving haemostatic resuscitation according to current standard of care.Trial registration: EudraCT no. 2014-003978-16 (22/1 2015); ClinicalTrials.gov: NCT02344069. Registered on 14 January 2015. Trial protocol version 4.2 (23-12-2014).