Background: With advances in the care of lymphoid cancers, there has been a recognized need for better measures of response. As a result, the assessment of minimal residual disease (MRD) has been increasingly incorporated into both clinical trials and routine patient management. MRD assessment is now recommended within several lymphoid cancer NCCN guidelines, including multiple myeloma (MM), ALL, and CLL. The clonoSEQ® Assay (Adaptive Biotechnologies; Seattle, WA) is currently the only FDA authorized MRD test available for bone-marrow assessment in patients with B-cell ALL and MM. While MRD findings are commonly reported within clinical trials, there has to-date been a limited ability to understand patient MRD testing patterns in the real-world care setting. Adaptive’s database provides a unique perspective on how MRD is being incorporated into guideline-supported care in the US. This study examined the use of MRD in MM and B-ALL patients within the Adaptive database. Methods: The study population included a de-identified internal dataset of our clonoSEQ clinical samples from January 2018 to October 2019. Patients who had a trackable sequence identified in a baseline (ID) clonality assessment were included in the analysis. Demographics, MRD testing patterns, and deepest level of MRD response were evaluated. Results: From Jan 2018 to Oct 2019, we reported MRD results for 1,369 patients with MM and 704 patients with B-ALL. The age distribution of patients with MRD testing performed (MM median age=65; B-ALL median age = 25) was generally consistent with epidemiologic data. Over the time period represented in this dataset, 47.5% of MM patients and 78.4% of B-ALL patients were observed to have reached MRD response of at least <10-5. 30.6% of MM patients and 68.7% of B-ALL patients achieved even deeper response, below 10-6. Conclusions: This real-world analysis demonstrates the growing use of MRD assessment in routine patient management, consistent with NCCN guidelines. Given the association between MRD levels and long-term outcomes demonstrated across clinical trials and meta-analyses in lymphoid cancers, the ability to capture and report patient MRD values using a quantitative and standardized assay in a large real-world population presents important opportunities for understanding lymphoid cancer population health, and performing comparative effectiveness and other RWE studies.