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PURPOSE: We performed a nationwide registry-based analysis to describe the clinical outcome of adults patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) who underwent an allogeneic hematopoietic stem cell transplantation (HSCT) after a TKI-based treatment. PATIENTS AND RESULTS: A total of 441 patients were included in the study. The median age at HSCT was 44 years (range 18-70). All the 441 patients (100%) received TKI before the HSCT (performed between 2005 and 2016). Of these patients, 404 (92%) were in cytologic complete remission (CR), while the remaining 37 (8%) had an active disease at the time of HSCT. Molecular minimal residual disease (MRD) was negative in 147 patients (36%) at the time of HSCT. The donor was unrelated in 46% of cases. The prevalent source of stem cells was peripheral blood (70%). The conditioning regimen was myeloablative in 82% of cases (TBI-based in 50%) and included ATG in 51% of cases. With a median follow-up after HSCT of 39.4 months (range: 1-145), the overall survival (OS) probability at 1, 2 and 5 years was 69.6%, 61.1% and 50.3%, respectively, with a median OS of 62 months. Progression-free survival (PFS) at 1, 2 and 5 years was 60.2%, 52.1% and 43.7%, respectively. OS and PFS were significantly better in patients with CR and MRD-negative at the time of transplant compared with those of patients with CR but MRD-positive (50% OS not reached vs. 36 months, P=0.015; 50% PFS not reached vs. 26 months, P=0.003). The subgroup of MRD-negative patients both at HSCT and at 3 months after HSCT had a better outcome (5 years OS rate 70%). Conversely, the 37 patients who underwent a HSCT with active Ph+ ALL had a median OS and PFS of 7 and 5 months, respectively. The 5 years cumulative incidence of relapse was significantly lower in MRD-negative patients (19.5% vs. 35.4%, P=0.001). The non-relapse mortality (NRM) after 1, 2 and 5 years was 19.1% (95%CI: 15.5-22.9), 20.7% (95%CI: 17-24.7) and 24.1% (9