Purpose: Ringer's lactate is used for patient resuscitation. Lactate naturally occurs in 2 stereoisometric forms, d- and l-lactate, that are added to fluid in equal amounts. Animal studies have demonstrated potentially deleterious effects of d-lactate on vital organs. Using an administrative database, we examined whether d- or l-lactate volume was associated with mortality in patients with trauma. Basic procedures: The Trauma and Injury Severity Score could be calculated in 24 616 of 528 219 patients admitted in 2006 to 2009. Demographic characteristics, the use of blood products, mechanical ventilation, and mortality were compared among the following 3 groups of patients administered Ringer's lactate: group 1, fluids other than Ringer's lactate; group 2, fluids including Ringer's dl-lactate; and group 3, no d-lactate. The mean volume (in millimoles per day) of d- and l-lactate administered was calculated. Multivariate analyses were used to measure the impact of lactate volume on mortality, and mechanical ventilation started more than 48 hours after admission. Main findings: Groups 2 and 3 consisted of 2 827 (11.5%) patients (88 hospitals) and 12 036 (48.9%) patients (145 hospitals), respectively. The use of mechanical ventilation best explained the variation in mortality. Greater d-lactate volume, but not fluid management category or l-lactate volume, was associated with mortality. l-Lactate decreased and d-lactate increased the use of mechanical ventilation more than 48 hours after admission. Conclusions: Because early administration of d-lactate was associated with mortality and ventilation, physicians and policy makers should recognize the advantages of l-lactate and encourage research on the quality of d- and l-lactate in case mixes beyond trauma.