Introduction: Although resuscitation guidelines for injured patients favor blood products, crystalloid resuscitation remains a mainstay in prehospital care. Our understanding of contemporary prehospital crystalloid (PHC) practices and their relationship with clinical outcomes is limited. Methods: The Pragmatic, Randomized Optimal Platelet and Plasma Ratios trial data set was used for this investigation. We sought to identify factors associated with PHC volume variation and hypothesized that higher PHC volume is associated with worse coagulopathy and a higher risk of acute respiratory distress syndrome (ARDS) but a lower risk of acute kidney injury (AKI). Subjects were divided into groups that received <1,000 mL PHC (PHC<1,000) and ≥1,000 mL PHC (PHC≥1,000); initial laboratory values and outcomes (ARDS and AKI risk) were summarized with medians and interquartile ranges or percentages and compared using Wilcoxon rank-sum tests and chi-square tests. The primary outcome was ARDS risk. Multivariable regression was used to characterize the association of each 500 mL aliquot of PHC with initial laboratory values and clinical outcomes. Results: PHC volume among study subjects (n = 680) varied (median, 0.3 L; interquartile range, 0–0.9 L) with weak associations demonstrated among prehospital hemodynamics, intubation, Glasgow Coma Score, and Injury Severity Score (0.008 ≤ R2 ≤ 0.09); prehospital time and enrollment site explained more variation in PHC volume with R2 values of 0.2 and 0.54, respectively. Compared with PHC<1,000, PHC≥1,000 had higher INR, PT, PTT, and base deficit and lower hematocrit and platelets. The proportion of ARDS in the PHC≥1,000 group was higher than PHC<1,000 (21% vs. 12%, P < 0.01), whereas the rate of AKI was similar between groups (23% vs. 23%, P = 0.9). In regression analyses, each 500 mL of PHC was associated with increased INR and PTT, and decreased hematocrit and platelet count (P < 0.05). Each 500 mL of PHC was associated with increased ARDS risk and decreased AKI risk (P < 0.05). Conclusion: PHC administration correlates poorly with prehospital hemodynamics and injury characteristics. Increased PHC volume is associated with greater anemia, coagulopathy, and increased risk of ARDS, although it may be protective against AKI.