Introduction Recently, treatment outcomes have significantly improved for children with acute lymphoblastic leukemia (ALL), with 5-year survival rates over 85%. However, survival rates for adolescents with ALL are lower than that for their younger counterparts. Patients and Methods A total of 374 patients aged 1 to 18 years, with newly diagnosed ALL were enrolled in this study from January 2003 to December 2013 at Yeungnam region of Korea. We divided patients into two groups: younger children group aged 1 to 10 years (n=272), adolescents group aged 10 to 18 years (n=102). Results The 5-year event-free survival (EFS) and overall survival (OS) for adolescents group was 79.6% and 81.5% respectively, compared with 89.4% and 96.5% for younger children group. This was not due to an increased cumulative incidence of relapse (CIR) (5-year CIR: 14.6±3.8% vs. 8.8±1.8%; P = 0.723), but due to an increased incidence of treatment-related death [5-year cumulative incidence of death (CID): 13.2±3.4% vs. 2.7±1%; P = 0.001]. Adolescents were more likely to present with T-cell phenotype ( P = 0.011) and less likely to have the ETV6-RUNX1 fusion and hyperdiploid karyotype ( P=0.002 and P=0.012, respectively). Conclusion Adolescents were more likely to present at diagnosis with biologically higher risk disease and more likely to experience treatment-related complications than younger children. Therefore, this specific age group may need particular vigilance when receiving intense chemotherapy, as relapse-free survival is similar to younger children.