It is important that current techniques for the monitoring of minimal residual disease (MRD) in chronic lymphocytic leukemia (CLL) are validated to ensure sensitivity and accuracy. Here, Peter Hillmen, MBChB, PhD, FRCP, FRCPath, from the University of Leeds and Leeds Teaching Hospitals NHS Trust, Leeds, UK, talks about the two MRD measurements of note; flow cytometry and high-throughput sequencing. While the use of flow cytometry is easier with current clinical structures, high-throughput sequencing could offer improved sensitivity soon, though it could be the case that both methods would be utilized going forward. Prof. Hillmen was speaking from the British Society for Haematology (BSH) 2018 Annual Meeting in Liverpool, UK.