Objective: We sought to identify potential drivers behind resuscitative endovascular balloon occlusion of the aorta (REBOA) induced reperfusion coagulopathy using novel proteomic methods. Background: Coagulopathy associated with REBOA is poorly defined. The REBOA Zone 1 provokes hepatic and intestinal ischemia that may alter coagulation factor production and lead to molecular pathway alterations that compromises hemostasis. We hypothesized that REBOA Zone 1 would lead to reperfusion coagulopathy driven by mediators of fibrinolysis, loss of coagulation factors, and potential endothelial dysfunction. Methods: Yorkshire swine were subjected to a polytrauma injury (blast traumatic brain injury, tissue injury, and hemorrhagic shock). Pigs were randomized to observation only (controls, n = 6) or to 30 min of REBOA Zone 1 (n = 6) or REBOA Zone 3 (n = 4) as part of their resuscitation. Thromboelastography was used to detect coagulopathy. ELISA assays and mass spectrometry proteomics were used to measure plasma protein levels related to coagulation and systemic inflammation. Results: After the polytrauma phase, balloon deflation of REBOA Zone 1 was associated with significant hyperfibrinolysis (TEG results: REBOA Zone 1 35.50% versus control 9.5% vs. Zone 3 2.4%, P < 0.05). In the proteomics and ELISA results, REBOA Zone 1 was associated with significant decreases in coagulation factor XI and coagulation factor II, and significant elevations of active tissue plasminogen activator, plasmin-antiplasmin complex complexes, and syndecan-1 (P < 0.05). Conclusion: REBOA Zone 1 alters circulating mediators of clot formation, clot lysis, and increases plasma levels of known markers of endotheliopathy, leading to a reperfusion-induced coagulopathy compared with REBOA Zone 3 and no REBOA.