Aging is a complex process that negatively impacts the development of the different systems and its ability to function. Moreover, the Aging rate in humans is not the same, principally due to genetic heterogeneity and environmental factors. The aging rate is measured as the decline of functional capacity and stress resistance. Therefore, several attempts have been made to analyse the individual age, ( so-called biological age) compared to chronological age. The biomarkers of aging are age-related body function or composition, these markers aim to assess the biological age and predict the onset of age-related diseases and/or residual lifetime. Such biomarkers should help in one hand to characterise the biological age and on the other hand to identify individuals at high risk of developing age-associated diseases or disabilities. Unfortunately, most of the markers under discussion are related to age-related diseases rather than to age, so none of these markers discussed in literature is a true biomarker of aging. Hence, we discuss some disease-related biomarkers useful for a better understanding of aging and the development of new strategies to counteract it, essential for improving the quality of life of the elderly population.