Assessment of hydration status is complex and difficult to achieve. Few assessment methods have been validated to accurately measure the fluid compartments in the body, but they have little application in practice. Different techniques have been developed to determine hydration status for the use in clinical settings, but their diagnostic accuracy remains questionable. Since many experts argue that there is no 'gold-standard' technique and one can never be achieved, this paper describes both, the benefits and limitations of the available methods and their usability in assessing hydration status of the elderly.