Previous data suggested that allo-SCT might be an effective therapy in the setting of chemo-refractory/relapsed diseases because of the potent long-term immune-mediated tumor control. This retrospective study aimed to analyze the outcome of adult patients who received allo-SCT in a chemo-refractory/relapsed status. The series included 840 patients with active or progressive disease at the time of transplant. Median age was 50 years. With a median follow-up of 40 months, 3-year OS, disease-free survival (DFS), and non-relapse mortality rates were 29±2, 23±2, and 30±2%, respectively. At the last follow-up, 252 patients (30%) were still alive (of whom 201 were in CR (24%). In a Cox multivariate analysis, the use of a reduced-intensity conditioning (RIC) before allo-SCT and use of an HLA-identical sibling donor remained independently associated with a better OS (hazard ratio (HR)=0.82; 95% confidence interval (CI), 0.69-0.98, P=0.03; and HR=0.79; 95% CI, 0.66-0.93, P=0.006, respectively). Also, a diagnosis of myelodysplastic syndrome/myeloproliferative disorder, Hodgkin lymphoma and non-Hodgkin lymphoma compared with acute leukemia had a favorable impact on OS (HR=0.55; 95% CI, 0.45-0.68, P<0.0001; HR=0.49; 95% CI, 0.31-0.75, P=0.001; and HR=0.47; 95% CI, 0.35-0.63, P<0.0001, respectively). In conclusion, this study suggests that allo-SCT may be of benefit in some subgroups of patients with active or progressive hematological malignancies at the time of allo-SCT.