Introduction: Burn pathophysiology, fluid therapy and mortality have been assessed by various laboratory parameters including lactate and base deficit serum markers. This study targeted flame injured cohort with an objective to determine the significance of early acidosis, through measurement of three acid base indices at admission in predicting 5-day (early) mortality among the flame burned patients.Methodology: A cohort study. Eighty flame injured patients presenting within 24 hours of incident were assessed for arterial blood pH, lactate and base deficit (BD). Mortality was recorded until day 28. Receiver operating characteristics curves were drawn; area under curve, cut offs, sensitivities and specificities for BD, lactate and pH were determined for 5-day mortality. The cut offs were used to derive contingency tables for calculation of predictive values. Odds ratios were calculated at 95% confidence interval. 28 day survival curve was generated. Level of significance was <0.05.Results: 28-day mortality was 39%. Five-day mortality was 24%. The latter was predicted by a lactate level of 2.36 mmol/L, BD of -10.05 mmol/L and pH of 7.344 with 75%,74% and 95% sensitivities respectively. Odds of patients dying at these levels or worse were 6.3, 11.4 and 36.9 respectively all with significant p-values.Conclusion: Arterial pH, base deficit and lactate are good predictors of 5-day mortality among fire victims.