Abstract： Objective To investigate the relationship between serum miR-340-5p and stimulator of interferon gene(STING)levels in elderly patients with acute ischemic stroke and their condition and prognosis.Methods A total of 113 elderly pa-tients with acute ischemic stroke admitted to Handan Central Hospital from May 2020 to May 2022 were selected as the study group,and 113 normal healthy patients during the same period were selected as the control group,according to the neurological impairment was assessed according to the National Institutes of Health Stroke Scale(NIHSS)score on the day of admission(<6 scores as mild,6-<14 scores as moderate,≥14 scores as severe),and prognosis was assessed according to the modified Rankin scale(mRs)score after3 months of treatment[good prognosis(0-2 scores)and poor prognosis(≥3 scores)].The expression levels of serum miR-340-5p and STING were detected by real-time fluorescence quantitative PCR.The influencing factors of prognosis were analyzed by multivariate logistic regression.ROC curve was used to analyze the predictive value of serum miR-340-5p and STING for prognosis.Results The expression level of serum miR-340-5p in study group was lower than that in control group(P<0.05),and the expres-sion level of STING in serum was higher than that in control group(P<0.05).There were 37 cases with mild nerve defects,43 ca-ses with moderate nerve defects,and 33 cases with severe nerve defects.The expression level of serum miR-340-5p in patients with dif-ferent nerve defects was severe<moderate<mild(P<0.05),while the expression level of serum STING in patients with different nerve defects was severe>moderate>mild(P<0.05).There were 74 patients with good prognosis and 39 patients with poor prognosis.Serum STING level and NIHSS score at admission in the poor prognosis group were higher than those in the good prognosis group(P<0.05),while serum miR-340-5p level was lower than those in the good prognosis group(P<0.05).Multivariate lo-gistic regression analysis showed that serum miR-340-5p was the protective factor for prognosis(P<0.05),and serum STING and NIHSS scores were the risk factors(P<0.05).ROC curve showed that the combined prognostic area of serum miR-340-5p and STING was greater than that predicted by each index alone(P<0.05).Conclusion The expression levels of serum miR-340-5p and STING can both reflect the condition of elderly patients with acute ischemic stroke,and have certain clinical value in prognostic prediction.