The purposes of this review are to know the characteristics and physical changes of elderly person, and to give the information about elderly person when the geriatric physical therapy will be needed in Korea. Current literature on physiological changes that occur in humans owing to aging is reviewed. The musculoskeletal, cardiopulmonary, neurological, perceptual, gastrointestinal, endocrine and immunological systems are discussed. Also, The cognition, personality, and role changes are discussed. We are discussed the changes of aging; biological theory, psychosocial theory and environmental theory. The effects of disuse and of exercise are reviewed. Implications for geriatric physical therapy are suggested.