Interleukin-6 (IL-6) has been identified as a marker of ischemia. However, its association with bowel obstruction has not been studied. Fifty-seven patients diagnosed with bowel obstruction were evaluated in a prospective blinded study and managed either medically (n = 29) or surgically (n = 28) per decision of attending surgeon. Serum IL-6 levels were obtained at the time of diagnosis and serially during hospitalization. Mean IL-6 levels at the time of diagnosis were significantly higher in patients who required operation compared with medically treated patients (63.9 vs 19.6 pg/mL respectively; P = 0.027). Levels returned to those seen in medically treated patients 3 days after operation. There was no difference in temperature, white blood cell count, or lactic acid levels. Five patients required resection for ischemic bowel. Patients with ischemic bowel had significantly higher initial mean IL-6 (146.6 vs 45.9 pg/mL; P = 0.034) and lactic acid (23.6 vs 11.8 mg/dL; P = 0.035) at time of diagnosis compared with surgically treated patients without bowel ischemia. No difference in white blood cell count was seen. IL-6 was a sensitive predictor of patients with bowel obstruction requiring operation and for presence of ischemic bowel. IL-6 screening may allow for earlier and more selective operation potentially decreasing morbidity and mortality.