Clinicians often use a patient’s age to make treatment decisions in a wide range of clinical scenarios. However, chronological age is an unreliable predictor of individual’s risk posed by surgical procedures and therapeutic interventions. An individual’s rate of aging is strongly influenced by environmental, genetic, and lifestyle factors which are not accounted for by chronological age alone. In contrast, biomarkers of molecular age provide a snapshot of the overall health and resiliency of the body, thus allowing physicians to better know their patients and more accurately predict their health risks.