Over the years, the prognosis of adolescents treated for acute lymphoblastic leukemia (ALL) has improved. However, this age group still represents a challenge with an overall survival (OS) of 60% compared to 85% in younger children. Herein, we report the outcome of adolescents treated in the European Organisation for Research and Treatment of Cancer (EORTC) 58951 clinical trial. EORTC 58951 clinical trial included patients with de novo ALL between 1998 and 2008. For this study, we analyzed data of all adolescents between 15 and under 18. Data from 97 adolescents were analyzed, 70 had B-lineage and 27 had T-lineage ALL. The 8-year event-free survival (EFS) and OS for the B-cell precursor ALL cases were 72.3% (59.4%-81.7%) and 80.8% (67.4%-89.1%), respectively. For the T-lineage, the 8-year EFS and OS were 57.4% (36.1%-74.0%) and 59.0% (36.1%-76.2%), respectively. "B-other" ALL, defined as BCP-ALL lacking any known recurrent genetic abnormalities were more frequent in our adolescent population (52.8%) than in younger children (27.1%). Outcome of adolescents in the EORTC 58951 study is supporting the findings that adolescents have better outcome in pediatric compared to adults' trials. Nevertheless, in pediatric studies, adolescents still have a worse prognosis than younger children. Despite the fact that specific unfavorable characteristics may be linked to the adolescent population, a careful study and characterization of adolescents "B-other" genetic abnormalities in ALL is critical to improve the outcome of this population.