This brief review examines the influence of aging on skeletal muscle mass and strength and specifically highlights sex-related differences. It is well established that aging is associated with a significant decline in muscle strength that becomes functionally important by the seventh decade of life. Age-related strength losses are mainly secondary to decline in skeletal muscle mass in men and women. While women may experience earlier strength losses than men, overall, age associated decreases in strength are similar when controlling for muscle mass. Although men may experience greater losses of total muscle mass, recent evidence, however, points toward greater declines in muscle quality in older women. The implications and potential mechanisms for these differences are discussed.