Aging could be due to reduced ability to adapt to stress and/or aging of immune system. It is suggested that body cells (except germ cells and transformed cells) bear specific 'death' genes responsible for aging process. However, current concepts of free radicals (chemical intermediate) and aging, postulate that intermolecular linkages between degradation products of lipid oxidation (when free radical is a polysaturated fatty acid) results in inactive polymers interfering with cell activity which could be inactivated by natural or artificial antioxidants (e.g. vit.E, vit.C) With aging body composition and conformation changes resulting in diminished activity of vital organs and structural changes in the body involving skin, muscle, bones etc. with altered look, diminished movements, hearting, vision etc. However, changes in higher function cause decline in intelligence, memory, ability to take decision, slow reaction and decrease ability to learn new skills resulting in more rigid attitude in elderly. Balanced diet plays an important role in delaying aging process and sexual activity promotes active life span.