This session is intended to aid in the understanding and to interpretation of reference or normal values, particularly in neonatal and geriatric populations. Recommendations for reference values studies will be discussed along with details of how to perform such studies . The audience will learn how to use data from the literature and to differentiate between different clinical settings for a better clinical outcome. For example, the use of appropriate reference values in the elderly population is important to provide a correct understanding of their clinical picture. A broader knowledge of this issue will help course attendees to avoid misleading clinical decisions and incorrect patient treatments.