Objective:To investigate the efficacy and safety of cladribine-based regimen for treatment of refractory/relapsed acute lymphoblastic leukemia (ALL).Methods:The clinical data of 11 patients with refractory/relapsed ALL treated with 1 course of CLAG (cladribine+cytarabine+granulocyte colony-stimulating factor) regimen from January 2018 to July 2022 were retrospectively analyzed. The efficacy and safety were summarized.Results:Among the 11 patients with refractory/relapsed ALL, there were 7 males and 4 females with a median age of 28 years (4-58 years). There were 8 cases of B-ALL, 1 case of acute mixed cell leukemia, and 2 cases of acute early precursor T-lymphocytic leukemia; 1 patient had TP53 mutation, 2 patients had NOTCH1 mutation, 2 patients had KRAS mutation, and 2 patients had NRAS mutation; 1 case had hyperdiploid chromosome and 1 patient had complex chromosome karyotype. Among the 11 patients, 4 cases received CLAG + liposomal doxorubicin,1 case received CLAG + idarubicin (IDA) + etoposide regimen, 1 case received CLAG + etoposide regimen, and 1 case received CLAG + pegaspargase injection+etoposide regimen, 1 case received CLAG + methotrexate + etoposide regimen,1 case received CLAG + liposomal doxorubicin + daratumumab regimen, 1 case received CLAG + IDA regimen,and 1 case received CLAG + chidamide. Among the 11 patients, 5 cases achieved complete remission, 1 case achieved partial remission and 5 achieved non-remission. The main adverse effects were severe myelosuppression (11 cases), agranulocytosis accompanied with fever (6 cases), septicemia (3 cases), and no treatment-related death occurred.Conclusions:cladribine-based regimen is effective in treating refractory/relapsed ALL. It has favorable safety and tolerance for patients.