Abstract： Objective To observe the effects of hydroethyl starch (HES 130/0.4) on serum interleukin-8, endothelin-l(ET-1) and myocardial myeloperoxidase activity (MP0) in rabbits subjected to ischemia-reperfusion, and to explore its possible mechanism. Method Thirty-six rabbits were randomly divided into three groups: lac-tated Ringer's solution group (group A, n= 12), 5% human albumin group (group B, n= 12) and 6% hy-droethyl starch group (group C, n= 12) Hie myodardial ischemia/reperfusion (MI/R) model was established by clamping left anterior descending coronary artery for 30 minutes followed by reperfusion for 180 minutes. Fifteen minutes prior to reperfusion, animals of these 3 given groups were ifused vis right internal jugular vein with 6 ml/kg lactated Ringer'solution, 5% human albumin and hydroethyl starch, respectively. Blood samples were obtained before occlusion (I_0),30 minutes after occlusion (I_1), 60 minutes (R_1) and 180 (R_2) minutes after reperfusion to determine the activities of serum lactate dehydrogenase (LDH), serum creatine phosphokinase (CPK), serum interleukin-8(IL-8) and endotheun-1 (ET-1).The size of myocardial infarction (MI),myocardial water content and myoloperoxidase activity (MPO) were examined as well.Statistical analyses were performed by using SPSS 12.0 software. Multiple comparisons were analyzed by using one-way analysis of variance (SNK- qtest). P ＜ 0.05 was considered statistically significant. Results The serum IDH, CPK,IL-8 and ET-1 weregradually increased after reperfusion, however, 180 min after reperfusion all serum biomarkers in 6% hydroethylstarch group (group C) were significantly lower than those in Iactated Ringer's solution group (group A) [(181 ±17) U/lvs. (334±39) U/L; (1927±205) U/L vs. (2987±326) U/L; (5.03±1.16) ng/L vs. (6.96±1.21) ng/L; (380±78.4) ng/L vs. (667.2±82.1) ng/L. all P ＜0.05], and than those in 5% human albu-min group (group B) [(181 ±17) U/L vs. (320±38) U/L; (1727 ±205) U/L vs. (2218 ±290) U/L; (5.03 ±1.16) ng/L vs. (5.90±1.03) ng/L; (380.9±78.4) ng/L vs. (615.6±80.2) ng/L, all P ＜0.05]. Theactivity of MPO of ischemic area in group C (0.20 ± 0.09 ng/L) was significantly lower than that in group A(0.48±0.15 ng/L) and in group B (0.37 ±0.12 ng/L) (P ＜ 0.05). Myocardial water content and infarct sizeof heart found in group C were significantly smaller than those in both group A and group B (P ＜ 0.05). Conclu-sions The 6% hydroethyl starch exhibits its protective effects on myocardial ischemia-reperfusion injury by pre-venting the production and release of serum IL-8 and ET-1, decreasing neutrophil infiltration capillary permeabilityand improving microvascular circulation.