Since ancient times, men tried to slow down the process of aging. This was done mainly by dietary means, and since the work of McCay and coworkers, it is general knowledge that caloric restriction is the most reliable technique in prolonging life of laboratory animals. To date, the importance of DNA-methylation, its influence on the three-dimensional structure of the genomic DNA, and the importance of growth factors on the process of aging are well known. Many of these factors modify the velocity of both transcription and cell growth and promote transformation of aging cells. First studies with growth hormone have been performed to investigate its influence on the process of aging.