<p>Anti-ageing medicine is a new movement in healthcare with one of its main objectives focused on the development of pharmaceuticals capable of extending both lifespan and healthspan. Before these drugs can be made available, their efficacy must first be demonstrated, which requires measuring ageing. This paper analyses the two main ways of doing this. The first, traditionally used in ageing studies, is called chronological and focuses on metrics such as overall survival or maximum lifespan. The idea is that the better the results a group of people shows in these metrics, the less ageing they have experienced, and the more potent the anti-ageing effect of the medicine being investigated. The second method, which emerged as an alternative to the problems of the first, is termed biological and aims to identify reliable biomarkers of ageing to assess the state of an individual or a population. While this last approach offers epistemic benefits that could allow it to play a relevant role in routine healthcare, the same does not apply to the generation of information in clinical research. In addition, practically speaking, both methods present similar problems due to the extended timespan of the human life cycle, generating very high demands on temporal resources. For these reasons, neither approach can be considered better than the other regarding the development of anti-ageing pharmacology. Notably, one significant consequence that arises from this is that realizing the full potential of anti-ageing medicine within the current <i>status quo</i> could be considered a potentially unattainable task.</p>