The Minimal Residual Disease (MRD) testing market covers highly sensitive diagnostic methods used to detect low levels of cancer cells that remain after treatment, helping clinicians assess depth of response, predict relapse risk, and refine therapy decisions. MRD testing is most established in hematologic malignancies—such as acute lymphoblastic leukemia, acute myeloid leukemia, multiple myeloma, and chronic lymphocytic leukemia—where residual disease can be quantified in bone marrow or peripheral blood using advanced molecular and cytometric techniques. Core applications include response assessment after induction and consolidation, post-transplant monitoring, risk-adapted therapy escalation or de-escalation, and surveillance during remission. End users include tertiary cancer centers, hospital laboratories, specialized reference labs, and clinical trial sponsors using MRD as a biomarker in drug development. Major technology formats include multiparameter flow cytometry, quantitative PCR and digital PCR, and next-generation sequencing (NGS) approaches, with growing interest in blood-based “liquid MRD” using circulating tumor DNA (ctDNA) for selected cancers and monitoring contexts.