PURPOSE: Despite the utility of serum lactate for predicting clinical courses, little information is available on the topic after decompressive craniectomy. This study was conducted to determine the ability of perioperative serum lactate levels to predict in-hospital mortality in traumatic brain-injury patients who received emergency or urgent decompressive craniectomy. METHODS: The medical records of 586 consecutive patients who underwent emergency or urgent decompressive craniectomy due to traumatic brain injuries from January 2007 to December 2014 were retrospectively analyzed. Pre- and intraoperative serum lactate levels and base deficits were obtained from arterial blood gas analysis results. RESULTS: The overall mortality rate after decompressive craniectomy was 26.1 %. Mean preoperative serum lactate was significantly higher in the non-survivors (P = 0.034) than the survivors but had no significance for predicting in-hospital mortality in the multivariate regression analysis (P = 0.386). Rather, preoperative Glasgow Coma Score was a significant predictor for in-hospital mortality (hazard ratio 0.796, 95 % confidence interval 0.755-0.836, P < 0.001). CONCLUSION: Preoperative lactate level is not an independent predictor of in-hospital mortality after decompressive craniectomy in traumatic brain-injury patients.