Profound nonhemorrhagic shock developed in one postoperative and two trauma patients. Cardiovascular collapse was characterized by severe hypotension (systolic blood pressure less than 80 mm Hg), hyperdynamic cardiac indices (CI greater than 4 L/min/m2), low systemic vascular resistance (SVR less than 500 dyne.sec/cm5.m2), and multiple organ failure. Sepsis was not found by culturing of specimens or visual inspection at laparotomy. Screening cortisol levels were low (less than 2 micrograms/dL in two patients) and did not respond appropriately to synthetic ACTH (cosyntropin) challenge. Administration of exogenous glucocorticoids promptly and dramatically reversed shock and organ failure in two patients. Oral glucocorticoid and mineralocorticoid supplementation were required at hospital discharge. Acute adrenal insufficiency is rare after trauma, but may produce life-threatening cardiovascular collapse, mimicking the "septic" shock state. Cosyntropin stimulation testing confirms the diagnosis and is accurate in traumatized patients. Outcome is dependent upon early recognition and exogenous glucocorticoid administration. Appropriate endocrine evaluation prevents unnecessary use of steroids in a population of trauma patients who are already in a state of immunosuppression.