Current therapeutic approaches for plasma cell myeloma attain an overall survival of more than six years for the majority of newly diagnosed patients. Novel effective treatments are being developed at an unprecedented rate for these patients but are becoming available at a very slow rate. This is because randomized phase 3 clinical trials take years to show a benefit using progression free survival (PFS) and overall survival (OS) as study endpoints. PFS and OS are currently the only accepted FDA endpoints for demonstrating drug efficacy. Recognizing the increasing gap between drug development and approval regulatory bodies are now investigating whether biomarker evaluation of response, such as measurement of minimal residual disease (MRD) as assessed by flow cytometry, can provide an early, robust prediction of survival and so improve the pace and cost of the drug approval process. Over the past decade, several publications have emerged demonstrating enhanced prediction of outcome using flow MRD testing for multiple myeloma over conventional response assessments. In these studies, flow cytometry demonstrated independent prediction of progression-free and overall survival. To be clinically useful and acceptable as a surrogate for PFS and OS by the FDA a standardized, reproducible assay that can be performed in multiple laboratories is required. Recently a group with participants from the ICCS, NIH, EuroFlow, and FDA published consensus guidelines for flow-MRD in multiple myeloma. This working group, building on the published studies showing correlation with outcomes, has established a standardized methodology, 8 color antibody panel with a minimum sensitivity of 0.01% and an upper sensitivity of 0.001%. This presentation will review the treatment options for multiple myeloma, current standards for measuring treatment responses, the application of flow cytometry to this problem and the development of a consensus for a harmonized procedure to evaluate MRD by flow.