Background: Multiple myeloma is a heterogenous disorder ith varied responses to chemotherapy. The response criteria are defined based on biochemical assays, bone marro  BM  examination, flocytometry and molecular assays. Lately PETCT is employed in MRD analysis. We aimed at studying the correlation of 18F-FDG-PETCT ith various biochemical markers, bone marro plasma cells, and flocytometry MRD analysis as a cross-sectional comparison at a given time point in patients post myeloma therapy. Methods: This is a single-center non-interventional study as part of PIPET-M trial. Patients of multiple myeloma underent 18F-FDG-PETCT, biochemical evaluation including  SPEP, UPEP, SIFE, SFLC, x3B2;2M, LDH  and BM examination  for plasma cells percentage and flocytometry for MRD  as part of end of treatment analysis. Patients ere included after induction chemotherapy, pre-autologous transplant  ithin 30 days  or post-transplant  Day 100  for analyzing efficacy of therapy. PET- positivity as based on the PIPET-M staging  A validated staging system developed by the authors . Results: A total of 72 patients ere screened of hich 52 patients underent PETCT, biochemical evaluation including  SPEP, UPEP, SIFE, SFLC, x3B2;2M and LDH  and bone marro examination. Concurrent flocytometry for MRD as done only in 11 patients. PET positivity had no relation ith the pre transplant biochemical markers  SPEP, UPEP, SIFE  [x3C7;2 -  1, 53 -0.34, p-0.56;  1, 52  - 2.18, p-0.14;  1, 52   0.32, p-0.57 respectively] or BM plasma cell percentage  p-0.64 . In PET positive patients, x3B2;2M and LDH ere higher  p - 0.032 , hereas SFLC ratio though higher as not statistically significant  p-0.61 . There as a good agreement beteen PET positivity and MRD by flocytomtery  Cohens x3BA; - 0.662, p lt 0.001 . Conclusions:18F-FDG-PETCT is a good marker for MRD analysis ith good agreement ith flocytometry and disease activity markers such as x3B2;2M LDH. Its poor correlation ith SPEP, UPEP, SIFE and BM plasma cell percentage can be secondary to undetectable levels of these markers in many patients  ~ 84 percent  after therapy. A comparison of these markers for prognosticating PFSOS is further arranted. Clinical trial information: U1111-1177-8850, REF201512010356.,J Clin Oncol 34, 2016  suppl; abstr 8029 ,U1111-1177-8850, REF201512010356,00:00.0,Hematologic MalignanciesPlasma Cell Dyscrasia