Longevity as a result of prolonged or postponed ageing is substantially influenced by genetic determinants. Most of them were analyzed by studying different progeria syndromes and their genetic control. From this point of view the use of experimental animals, because it enables to identify genes involved in shortening or prolongation of life-span by changing experimental conditions, has been also very effective. Expression of ageing processes at cellular as well on organism level as a biological unit revealed sets of genetic pathways involved in longevity. Several theories which elicit different aspects have been constructed to explain the ageing process.