A quantitative analysis of capillary supply to skeletal muscle is important for understanding the upper limit of the capacity for delivery of oxygen and substrates to muscle cells. It has been well documented that the number of capillaries is altered by several factors including development, aging, and alteration of muscle activity level such as exercise training and inactivation. There is, however, a contradiction in animal studies for aging-related change in the number of capillaries. Human studies using biopsy technique also displayed an inconsistency on that point, in which capillary supply was not influenced or decreased with aging. This review discussed an inconsistency among studies for aging-related change in muscle capillary supply. In conclusion, the relationship between capillary supply and muscle fiber size is similar for both young and elderly population, and the morpho- logical balance between capillaries and each muscle fiber was maintained with advancing age.