The mechanism of final cessation of the reproductive life span has not been solved yet. It is generally assumed that the most important factor is ovarian follicular reserve. In ovaries at intrauterine period, a major factor that determines the number of the primordial follicle is the mitotic ability as well as the number of primordial germ cells, which migrate to gonadal ridge. The telomere length is one factor that determines the number of mitosis of the cell. The differences between the telomere lengths of same aged healthy women reflect the difference of the telomeres of the primordial germ cells at the intrauterine period. Women with long telomeres supposedly have had their primordial germ cells at the beginning of life with long telomeres. So, these cells should have had more mitotic division and more follicle numbers in the ovaries than the short ones. The aim of this study was to analyse the relation of the reproductive life span and telomere length. The telomere lengths of 37 women volunteers aged 50 years were measured by fiber FISH technique. A positive correlation was found between reproductive life span and the telomere length.