Background:Many studies showed a better recovery of cognitive function after administration of exogenous lactate during moderate-severe traumatic brain injury. However, the study evaluating lactate effect on mild traumatic brain injury is still limited.Aims:To evaluate the effect of exogenous lactate on cognitive function in mild traumatic brain injury patients.Settings and Design:Prospective, single blind, randomized controlled study on 60 mild traumatic brain injury patients who were undergoing neurosurgery.Materials and Methods:Subjects were randomly assigned into hyperosmolar sodium lactate (HSL) group or hyperosmolar sodium chloride (HSS) group. Patients in each group received either intravenous infusion of HSL or NaCl 3% at 1.5 ml/KgBW within 15 min before neurosurgery. During the surgery, patients in both groups received maintenance infusion of NaCl 0.9% at 1.5 ml/KgBW/hour.Statistical Analysis:Cognitive function, as assessed by Mini-Mental State Examination (MMSE) score at 24 h, 30 and 90 days post-surgery, was analyzed by Anova repeated measures test.Results:The MMSE score improvement was significantly better in HSL group than HSS group (P < 0.001). In HSL group the MMSE score improved from 16.00 (13.75-18.00) at baseline to 21.00 (18.75-22.00); 25.00 (23.75-26.00); 28.00 (27.00-29.00) at 24 h, 30, 90 days post-surgery, respectively. In contrast, in HSS group the MMSE score almost unchanged at 24 h and only slightly increased at 30 and 90 days post-surgery.Conclusions:Hyperosmolar sodium lactate infusion during mild traumatic brain injury improved cognitive function better than sodium chloride 3%.