Background Endurance activities induce cardiac hypertrophy also it was observed the hdac4 gene expression rate in skeletal muscle is affected by endurance activities.Purpose Therefore the aim of this study was to investigate the effect of endurance training on cardiac expression of HDAC4.Material and Methods For this purpose, 14 rats under controlled conditions (temperature, light/dark (12:12) cycle, with ad Libitum access to food and water) were housed and randomly was divided into control and Experimental groups, the experimental group performed 14-weeks endurance exercise on motorized treadmill, and then 48 hours after the end of the last session were anesthetized as sacrificed. The left ventricle of the heart was removed. Real time RT-PCR method was used to determine of expression levels of hdac4 gene, and the obtained data were evaluated using t-test.Results The results showed the mean of left ventricle hdac4 gene expression was higher in experimental group significantly (P=.002) than control group.Conclusion It appears differences in the type of left ventricle Hypertrophy is Due to difference in response of HDAC4 factor.