Background: Studying the effects of smoking intensity is important to evaluate the risk of tobacco use on a range of illnesses, such as as sarcopenia among the elderly. Thus, this study aimed to analyze the effects of pack-years of cigarette smoking on the diaphragm muscle (DIAm) histopathology of postmortem samples. Methods: Subjects were divided into three groups: never-smoker (n= 46); less than 30 pack-years of smoking (n= 12); and more than 30 pack-years of smoking (n= 30). Diaphragm samples were stained with Picrosirius red and hematoxylin and eosin stain for general structure. Results: Participants with more than 30 pack-years of cigarette smoking had a significant increase in adipocytes, blood vessels and collagen deposit, as well as an increase in histopathological alterations. Conclusions: Pack-years of smoking was associated with DIAm injury. However, further clinicopathological studies are needed to confirm our findings.