Background: Of the potentially survivable US battlefield deaths from 2001 to 2011, 80% to 91% were caused by severe hemorrhage. We subjected minipigs to acute severe blood loss, administered a single dose of 17α- ethynylestradiol-3-sulfate (EE-3-SO4) without resuscitative fluids, and determined survival as well as cardiovascular, biochemical, and physiologic response parameters. Methods: Following controlled removal of 60% circulating blood volume over 1 hour, minipigs received EE-3-SO4 at 0, 1, 3, or 5-mg/mL saline per kilogram of body weight in Experiment 1 (n = 25) and 0-, 0.1-, 0.3-, or 1-mg/mL saline per kilogram in Experiment 2 (n = 23). Survival times and response parameters were recorded for the next 6 hours. Results: Median survival times of the minipigs receiving 1 mg/kg (257 minutes and 360 minutes) were 1.8 times and 5 times those of the control group (140 minutes and 65 minutes) in Experiments 1 and 2, respectively. For both experiments combined, the log-rank p value was 0.0002, and the number of animals alive at 6 hours was 6 (50%) of 12 in the 1-mg/kg groups versus 0 (0%) of 12 in the control groups. Early increases in glucose, lactate, potassium, and phosphate as well as decreases in bicarbonate and mean arterial pressure correlated with shorter survival times. Conclusion: Administration of a single dose of 1-mg/kg EE-3-SO4 in 1-mL/kg of saline following severe hemorrhage increased survival in 60% acutely bled minipigs by 3.5-fold. Slightly elevated blood pressure values, more physiologic values of oxidative phosphorylation parameters, and lower elevations of possible tissue necrosis parameters correlated with longer survival time. These Results support the further product development of EE-3-SO4 for the indication of severe hemorrhage when standard resuscitative fluids are not available. © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.