The expression of atrogin-1/MAFbx, a muscle-specific E3 ubiquitin ligase, is high under catabolic conditions that result in muscle atrophy. We previously showed that expression of atrogin-1/MAFbx was expressed in skeletal, smooth and cardiac muscles of chickens and its expression in skeletal and smooth muscles was regulated by nutritional conditions. In this study, the effects of fasting and refeeding on the expression of atrogin-1/MAFbx and other proteolytic-related genes, including 20S proteasome C2 subunit, m-calpain large,subunit, and cathepsin B, in cardiac muscle of broiler chickens were investigated. Chickens were fasted for 24 h, and refed for 2 h. Atrogin-1/MAFbx mRNA expression was increased by fasting, but subsequent refeeding reduced the increase. The mRNA expression of the 20S proteasome C2 subunit and m-calpain large subunit mRNA was not affected by fasting or refeeding. Cathepsin B mRNA expression was increased by fasting, but unlike atrogin-1/MAFbx mRNA expression, the increase was not reduced by refeeding. These results demonstrate the muscle-specific ubiquitin ligase atrogin-1/MAFbx gene expression in cardiac muscle as well as skeletal and smooth muscles of chicken is regulated by food deprivation and nutritional supply.