Reliable preoperative diagnosis of intestinal necrosis in strangulating small bowel obstruction (SSBO) is difficult, and, as yet, no reliable marker has been described. We, therefore, retrospectively examined clinical symptoms and hematobiochemical data of patients with SSBO in our surgical wards. Thirty-seven patients with SSBO were analyzed in this study. They were divided into two groups: group A (13 patients), the presence of gangrenous intestine; and group B (24 patients), the absence of it. By means of chi2 test, Student t test, or Welch t test, peritoneal signs, white blood cell count (leukocytosis or leukopenia), systemic inflammatory response syndrome (SIRS), shock, and base deficit were significantly associated with whether gangrenous intestine existed or not. Next, in simple regression analysis, base deficit was significantly correlated with the length of gangrenous intestine. In stepwise logistic regression analysis, SIRS was independently correlated with the presence of gangrenous intestine. If SIRS or metabolic acidosis is seen in patients with SSBO, the intestine is certainly gangrenous.