© 2015 Wolters Kluwer Health, Inc. All rights reserved. BACKGROUND Reliance on prehospital trauma triage guidelines misses patients with serious injury. Lactate is a biomarker capable of identifying high-risk trauma patients. Our objective was to compare prehospital point-of-care lactate (P-LAC) with systolic blood pressure (SBP) for predicting the need for resuscitative care (RC) in trauma patients transported by ground emergency medical services. METHODS This is a prospective observational study at nine sites within the Resuscitation Outcomes Consortium conducted from March 2011 to August 2012. Lactate was measured on patients with a prehospital SBP of 100 mm Hg or less who were transported by emergency medical services to a Level I or II trauma center. Patients were followed up for the need for RC, defined as any of the following within 6 hours of emergency department arrival: blood transfusion of 5 U or greater; intervention for hemorrhage including thoracotomy, laparotomy, pelvic fixation, or interventional radiology embolization; or death. RESULTS A total of 387 patients had a lactate value and presented with SBP between 71 mm Hg and 100 mm Hg, and 70 (18%) required RC. With the use of a P-LAC decision rule (≥2.5 mmol/L) that yielded the same specificity as that of SBP of 90 mm Hg or less (48%), the observed sensitivities for RC were 93% (95% confidence interval [CI], 84-98%) for P-LAC of 2.5 mmol/L or greater and 67% (95% CI, 55-78%) for SBP of 90 mm Hg or less (McNemar's test, p < 0.001). P-LAC has an estimated area under the curve of 0.78 (95% CI, 0.73-0.83), which is statistically superior to that of SBP (0.59; 95% CI, 0.53-0.66) and shock index (heart rate / SBP) (0.66; 95% CI, 0.60-0.74). CONCLUSION P-LAC obtained at the scene is associated with the need for RC. P-LAC is superior to other early surrogates for hypoperfusion (SBP and shock index) in predicting the need for RC in trauma patients with 70 mm Hg < SBP ≤ 100 mm Hg. LEVEL OF EVIDENCE Prognostic study, level II.