The progression-free and overall survival for patients with Chronic Lymphocytic Leukaemia (CLL) has improved substantially over the past few decades, to the extent that cure is now increasingly considered to be an achievable goal. The level of measurable residual disease (MRD) at end of treatment is highly predictive of outcome and MRD assessment can provide a rapid way of identifying the optimal therapeutic approach in clinical trials. As a result, MRD is often a primary or secondary trial endpoint and the European Medicines Agency has identified MRD as an intermediate endpoint for licensing new drugs. The application of MRD for drug development is also under consideration by other regulatory agencies and guidance on using MRD in clinical trials could be adopted into routine clinical management, particularly for novel agent fixed-duration approaches that can eradicate MRD in the majority of patients. Potential applications of MRD for routine practice include guiding the duration of treatment, identifying patients who may benefit from introduction of maintenance/consolidation strategies, and monitoring patients in remission. The optimal use of MRD analysis in CLL (and other disorders) requires an appreciation that the level of disease is much more informative than determining whether MRD is above or below an arbitrary threshold. It is also important to understand the relative merits of different technologies for MRD measurement. This presentation will consider practical examples of applying MRD technology to improve patient outcomes.