Abstract: Objective：To evaluate the diagnostic value of serum procalcitonin (PCT), C-reactive protein (CRP), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) and interleukin-6 (IL-6) in early-onset stroke associated pneumonia (EOP) in elderly patients. Methods：Patients with acute stroke admitted to geriatrics department in Shanghai Fifth People’s Hospital from January 2015 to December 2016 were included and divided into EOP group and control group (without infection). The levels of PCT, CRP, sTREM-1, IL-6 in serum and Clinical Pulmonary Infection Score (CPIS) in all subjects were determined 2 h, 24 h，and 48 h after admission. The dynamic trend of inflammatory indicators in EOP patients at different time points was analyzed. The diagnostic efficacy of different indicators for EOP was analyzed by ROC curve, and the correlations between inflammatory indicators and EOP was explored. Results：Among 536 patients with acute stroke, 153 patients were diagnosed as EOP with incidence of 28.54%. The levels of PCT, CRP, sTREM-1, IL-6 in serum and CPIS in EOP group were significantly higher than those in control group at 24 h time points (all P<0.05). In EOP group, PCT and sTREM-1 reached peak at 24 h and began to decline at 48 h, IL-6 peaked at 2 h and decreased continuously at 24 h and 48 h, CRP increased significantly at 24 h and remained at high level at 48 h, CPIS increased gradually at 24 h and 48 h. The efficacy in diagnosing EOP was preferable at 2 h for IL-6 with AUC of 0.930, at 24 h for sTREM-1 and PCT with AUC of 0.957 and 0.936, at 48 h for PCT and sTREM-1 with AUC of 0.847 and 0.837. The results of multivariate Logistic regression showed that the levels of PCT and sTREM-1 were significantly correlated with EOP (P<0.05). Conclusions：For acute stroke patients, detection of IL-6 2 h after admission combined with detection of PCT and sTREM-1 24 h after admission can improve the early diagnosis accuracy of EOP.