Objective. To investigate the dynamic changes of serum vascular endothelial growth factor(VEGF) levels in a rat model of acute myocardial infarction. Materials and methods. Eighty-eight adult male Sprague-Dawley rats weighing approximately 270 g were used in this study. Eighty rats were subjected to left coronary artery ligation, with 8 rats for each different duration of infarct.Eight sham-operated animals in which the left coronary artery was surgically exposed without ligation were used as con-trols. Blood samples were drawn from the right atrium before ( sham animals ) and 1,3,6,12,24 h and 2,3,5,7,14 dafter myocardial infarction. The concentrations of serum VEGF were measured by a sensitive enzyme-linked im munosorbent assay with a rabbit polyclonal antibody specific for VEGF. Results. In the 8 control animals, the mean concentration of serum VEGF was 66.99 ± 17.83 pg/ml. Six hours after myocardial infarction, the level of serum VEGF significantly increased to 125.68 ± 28.07 pg/ml ( P ＜0.01 vs.sham controls), and reached a peak (240.61 ± 70.63 pg/ml. P ＜0.01 vs. sham animals) at 24 h after ligation andthen decreased gradually over the remaining 2 weeks. However, the level remained significantly elevated for 14 d(107.64±30.13pg/ml, P＜0.01 vs. sham controls). Condusion. The present study shows that the levels of serum VEGF are markedly increased until 14 d in the ratmodel of acute myocantial infarction. The increased serum VEGF level may play an important role in the angiogencsisassociated with myocardial infarction.