Coagulopathic bleeding is a serious complication of cardiac surgery. A very low preoperative plasma fibrinogen level (PFL) has been previously described as a risk factor for red blood cell (RBC) transfusion in the perioperative setting. Nevertheless, contradictory results have been published concerning preoperative fibrinogen infusion to decrease RBC transfusion. These results highlight the need for a better description of the relation between preoperative PFL and RBC transfusion. In this single-centre retrospective study, we showed that both high and low PFLs are associated with an increase in RBC transfusion. A pro-inflammatory preoperative status could be involved in the association between high PFL and the increase in RBC transfusion. This non-linear relation between PFL and RBC transfusion could explain the difficulty of decreasing postoperative bleeding using only an algorithm aimed at increasing preoperative PFL.