Emergency or urgent surgery, which can be defined as surgery which must be done promptly to save life, limb, or functional capacity, is associated with a high risk of bleeding and death. Antifibrinolytic agents, such as tranexamic acid, inhibit blood clot breakdown (fibrinolysis) and can reduce perioperative bleeding. Tranexamic acid has been shown to reduce the need for a blood transfusion in adult patients undergoing elective surgery but its effects in patients undergoing emergency or urgent surgery is unclear. To assess the effects of tranexamic acid on mortality, blood transfusion and thromboembolic events in adults undergoing emergency or urgent surgery.We searched the following electronic databases: the Cochrane Injuries Group's Specialised Register (22 August 2012); Cochrane Central Register of Controlled Trials (2012, issue 8 of 12); MEDLINE (Ovid SP) 1950 to August Week 2, 2012; PubMed 1 June 2012 to 22 August 2012; EMBASE (Ovid SP) 1980 to 2012 Week 33; ISI Web of Science: Conference Proceedings Citation Index-Science (CPCI-S) 1990 to 22 August 2012; ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED) 1970 to 22 August 2012. We also searched online trial registers on 22 August 2012 to identify unpublished studies.Randomised controlled trials comparing tranexamic acid with no tranexamic acid or placebo in adults undergoing emergency or urgent surgery.Two authors examined titles, abstracts and keywords of citations from the electronic databases for eligibility and extracted data for analysis and risk of bias assessment. Outcome measures of interest were mortality, receipt of a blood transfusion, units of blood transfused, reoperation, seizures and thromboembolic events (myocardial infarction, stroke, deep vein thrombosis and pulmonary embolism).We identified five trials involving 372 people that met the inclusion criteria. Three trials (260 patients) contributed data to the analyses. The effect of tranexamic acid on mortality (RR 1.01; 95% CI 0.14 to 7.3) is uncertain. However, tranexamic acid reduces the probability of receiving a blood transfusion by 30% although the estimate is imprecise (RR 0.70; 95% CI 0.52 to 0.94). The effect on deep venous thrombosis (RR 2.29; 95% CI 0.68 to 7.66), and stroke (RR 2.79; 95% CI 0.12 to 67.10) is uncertain. There were no events of pulmonary embolism or myocardial infarction. None of the trials reported units of blood transfused, reoperation, or seizure outcomes.There is evidence that tranexamic acid reduces blood transfusion in patients undergoing emergency or urgent surgery. There is a need for a large pragmatic clinical trial to assess the effects of routine use of tranexamic acid on mortality in a heterogeneous group of urgent and emergency surgical patients.