Current response criteria for evaluating hematologic response in light chain (AL) amyloidosis do not require a bone marrow examination to evaluate for residual plasma cells [1]. Complete response (CR) is defined as achieving a normal free light chain (FLC) ratio and negative immunofixation in serum and urine. In a study of multiple myeloma patients [2], 10% of patients achieving all the serum criteria for stringent CR by conventional International Myeloma Working Group (IMWG) response criteria [3] had increased plasma cells in the bone marrow. Moreover, patients who had less than 5% plasma cells in the marrow had better outcomes, thereby reinforcing the importance of bone marrow biopsy in response evaluation in multiple myeloma. More recently, it has been demonstrated than achieving even deeper responses with minimal residual disease (MRD) negativity is associated with superior survival outcomes in multiple myeloma [4, 5]. Recent work from our institution in AL amyloidosis found that in patients achieving a very good partial response, those with less than 0.1% monotypic plasma cells in the bone marrow on six color multi-parametric flow cytometry displayed a trend towards better PFS [6].