Abstract: This study was performed on human muscle autopsies, from triceps of the left arm, obtained from 23 non-athletic built males, with no evidence of neuromuscular involvement. Their age covered the range from one month to 81 years. They were divided into four groups according to their age namely, the infant, the child, the adult and the elderly groups. The autopsy specimens were processed for light and transmission electron microscopical study. As for light microscopy, they were subjected to hematoxylin and eosin and Masson trichrome staining methods. An image analysis study was included to estimate the mean cross sectional area of the muscle fiber, the mean area percent of the fibrocollagenous septa enclosed between the muscle bundles and the mean satellite cell counts. The study revealed the presence of considerable variations in the histological structure of the skeletal muscle with the advancement of age. The cross sectional area of the skeletal muscle fiber reached its peak value in the adult group followed by marked regression in the elderly group. An expected continuous spectrum of growth and maturation was observed in the fibrocollagenous septa between the muscle bundles. These septa became densely packed and irregular in the elderly age group. The maximum number of satellite cells was observed in the child group followed by a decline in the adult group to become scarce and pyknotic in the elderly one. Ultrastructurally, in senescent individuals, the sarcolemma appeared irregular, with irregular arrangement of the dark and light bands and the mitochondrial aggregates appeared ballooned and degenerated. These observations could suggest that muscle atrophy is a major contributor to the decrease in muscle strength manifesting with advancement of age.