A gradual change of molecules that are related in fission and fusion is occurred during aging process. Although aging effects on mitochondrial fusion and fission are investigated, it is still unclear that the extent of the change in mitochondria fusion and fission periodically. In this study we investigated the changes of mitochondrial proteins involved in fusion (Mfn2, Opa1) and fission (Drp1, Fis1) in the human gracilis muscle ranging from 10 to 50 years of age (n=40). The gracilis muscle showed a significant increase in muscle apoptotic changes in the age of 50s compared with 10s by using in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The expression levels of Drp1 and Fis1 (P<0.01, P<0.05) mRNA were significantly elevated and the Mfn2 and Opa1 (P<0.01, P<0.05) levels were decreased from older individuals. The ratio of fission and fusion was altered and the level of increment of fission gene was greater than fusion gene decrement in the age of 50s. These findings suggest that changes of mitochondrial fusion and fission proteins related with aging might contribute to aged muscle apoptosis.