ObjectiveTo explore the clinical features and outcomes of relapsed acute lymphoblastic leukemia (ALL) in children. MethodsThirty-two ALL children treated in line with the Chinese Child Leukemia Cooperative Group ALL-2008 protocol with a relapse of the disease during January 2009 to May 2013 were enrolled into this study. Their clinical features and outcomes were retrospectively analyzed and compared with those who achieved continuous complete remission (CCR). ResultsThere were 32 relapsed cases among 319 newly diagnosed ALL cases (excluding infantile ALL) during the study period, with a relapse rate of 10%. In the relapse group, the proportions of patients with peripheral blood white blood cell count ≥50×109/L at diagnosis, positive BCR/ABL fusion gene, poor prednisone response, high risk stratification, and who failed to achieve bone marrow complete remission at d15 and d33 of induction chemotherapy, were significantly higher than those in the CCR group (all P<0.05). Multivariate analysis showed that high risk stratification was an independent risk factor for relapse (OR=3.529, P=0.002). In terms of site of relapse, isolated marrow relapse, isolated central nervous system relapse, isolated testicular relapse and combined relapse accounted for 23 (72%), 6 (19%), 1 (3%) and 2 (6%), respectively. As regard to the time of relapse, 26 cases (81%), 4 cases (13%) and 2 cases (6%) were categorized as very early relapse, early relapse and late relapse respectively. Twenty-four children with relapsed ALL received re-induction chemotherapy. Among them, 16 cases (67%) achieved second complete remission. Nevertheless, 9 cases ultimately suffered second relapse. ConclusionRelapse, which occurs more commonly in high risk ALL group, still remains a great challenge in clinical practice. Relapsed ALL, especially those with very early and early marrow relapse, has poor prognosis.