Objective:Central nervous system leukemia(CNSL)is one of the main causes of recurrence and death in patients with acute leukemia.This study aims to dynamically monitor minimal residual disease(MRD)in cerebrospinal fluid and bone marrow of patients with different types of acute leukemia by flow cytometry(FCM),and to compare the timeliness and consistency of MRD detection between the 2 methods to further explore the application value of monitoring MRD in cerebrospinal fluid. Methods:A total of 199 patients with acute leukemia admitted to the Guangdong Provincial people's Hospital between October 2018 and January 2022 were retrospectively analyzed,and multiparametric FCM method was adopted to summarize and analyze MRD in cerebrospinal fluid of patients with different types of leukemia and MRD in cerebrospinal fluid and bone marrow specimens of the same patients,and its role in assessing the prognostic value of patients was discussed. Results:Among the 199 acute leukemia cases,a total of 31 cases(15.58%)were positive MRD in the cerebrospinal fluid,of which 18 cases(58%)were detected earlier than the corresponding bone marrow specimens.Among the 19 patients with acute T lymphoblastic leukemia,134 patients with acute B lymphoblastic leukemia,and 46 patients with acute myeloid leukemia counted,there were 4,18,and 9 patients with positive MRD in the cerebrospinal fluid.The Kappa value of the concordance test between the results of cerebrospinal fluid MRD and bone marrow MRD in different types of acute leukemia was only 0.156,demonstrating a low concordance between them. Conclusion:Dynamic monitoring of cerebrospinal fluid MRD by FCM can be used as a monitoring index for central nervous system leukemia,and monitoring cerebrospinal fluid can detect MRD earlier compared with bone marrow,which complements each other as a sensitive index for evaluating prognosis with significant guidance in clinic.