While mantle cell lymphoma (MCL) can be an aggressive disease, there is a subgroup of patients whose disease poses low risk, thus treatment may not be required. Here, Simon Rule, MD, from Plymouth University, Plymouth, UK, discusses this indolent patient group at the 2018 Society of Hematologic Oncology (SOHO) Annual Meeting in Houston, TX. Prof. Rule explains the difficulties associated with defining this particular patient group, since there are no known baseline biological characteristics of indolent MCL. Prof. Rule also speaks about a large UK-based trial which aims to identify such baseline characteristics by closely monitoring newly diagnosed patients with MCL.