Objective To investigate the predicting value of intermedin (IMD) for the prognosis of elderly sepsis patients.Methods A retrospective analysis was conducted. Forty-one patients with sepsis, aged ≥65 years, and admitted to geriatrics intensive care unit of Aerospace Center Hospital from April 2015 to December 2016 were enrolled. Thirty healthy patients were studied as control during the same time. The expression of C-reactive protein (CRP), procalcitonin (PCT) and IMD were tested within 24 hours during hospitalization, and the acute physiology and chronic health evaluation Ⅱ(APACHE Ⅱ) score and prognosis was evaluated. According to APACHE Ⅱ score, patients were divided into 3 groups, 10-20 score, 21-30 score, and > 30 score group. And based on the prognosis, the patients were divided into death group and survival group. The differences of expression levels of CRP, PCT and IMD in each group were assessed. The relationship of IMD and infection index was analyzed by Pearson correlation. Receiver operating characteristic curve (ROC) was used to evaluate the prognostic value of CRP, PCT and IMD in patients with sepsis.Results Compared with the control group, the levels of CRP, PCT and IMD were significantly higher in the sepsis patients [CRP (mg/L): 114.71±40.08 vs. 4.03±2.68, PCT (μg/L): 1.338±0.812 vs. 0.007±0.001, IMD (ng/L):43.03±9.67 vs. 16.77±2.06, allP < 0.01]. With the increase of APACHE Ⅱ score, the levels of PCT and IMD were gradually increased. In APACHE Ⅱ 10-20 score, 21-30 score, > 30 score groups, PCT (μg/L) were 0.397±0.129, 1.164±0.326, and 1.999±0.888, respectively (F = 19.392,P = 0.000); IMD (ng/L) were 29.12±5.60, 40.48±4.40,52.75±4.73, respectively (F = 33.310,P = 0.000). There was no significant difference in CRP among APACHE Ⅱ score groups (F = 2.137,P = 0.132). The level of IMD was positively correlated with CRP and PCT (r1 = 0.351,P1 = 0.024;r2 = 0.617,P2 = 0.000), and there was no correlation with temperature and white blood cell count (r1 = 0.063,P1 = 0.697;r2 = 0.064,P2 = 0.692). The expression of PCT and IMD in the death groups were significantly higher than the survival group [PCT (μg/L): 1.547±0.883 vs. 1.043±0.608, IMD (ng/L): 47.44±8.23 vs. 36.80±8.13, bothP < 0.05], while CRP was not significantly different. The area under the ROC curve [AUC (95% confidence interval, 95%CI)] of IMD was larger than that of PCT and CRP [0.809 (0.675-0.943) vs. 0.680 (0.511-0.849), 0.664 (0.490-0.838)]; when cut-off value of IMD was 41.58 ng/L, the sensitivity was 75.0% and the specificity was 82.4%.Conclusions The levels of CRP, PCT and IMD were increased in elderly sepsis patients, and IMD and PCT can better reflect the severity of sepsis. IMD is more valuable in predicting the prognosis of sepsis patients.