Backgrounds: Effects of myocardial injury on E-selectin remain unclear. Thus, we investigated the diagnostic value of E-selectin for myocardial injury in paediatric patients with mycoplasma pneumoniae pneumonia. Methods: In this prospective and blinded clinical study, plasma E-selectin, cardiac troponin I, creatine kinase isoenzyme MB, interleukin-6 and tumor necrosis factor alpha concentrations were measured in paediatric patients with mycoplasma pneumoniae pneumonia (MPP group, n = 138). The control group comprised 120 healthy children. The definition of cardiac injury was based on cardiac troponin I or CK-MB (with or possibly without abnormal electrocardiogram evidence). Diagnostic value of E-selectin for myocardial injury was determined by analysing receiver operating characteristic curves. Results: Among the 138 mycoplasma pneumoniae pneumonia patients, 40 patients were identified with myocardial injury, while 98 patients were identified without myocardial injury. Plasma E-selectin concentrations were: 40.22 +/- 4.80 ng/mL, in patients with myocardial injury; 18.55 +/- 2.16 ng/mL, in patients without myocardial injury and 12.39 +/- 3.27 ng/mL, in healthy children. For the 40 patients identified with myocardial injury, area under the receiver operating characteristic curve value for plasma E-selectin concentrations was 0.945 (95% CI: 0.899-0.991), and optimal diagnostic cut-off value was 29.93 ng/mL (positive likelihood ratio = 72.5). Conclusion: E-selectin was shown to be an effective index for myocardial injury in paediatric patients with mycoplasma pneumoniae pneumonia, and its role in other causes of myocardial injury warrants further investigation.