Acute lymphoblastic leukemia (ALL) in second complete remission is one of the most common indications for allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients. We compared the outcome after HCST of adolescents, aged 14 to 18 years, with that of children (ie, patients < 14 years of age). Enrolled in the study were 395 patients given the allograft between January 1990 and December 2007; both children (334) and adolescents (61) were transplanted in the same pediatric institutions. All patients received a myeloablative regimen that included total body irradiation in the majority of them. The donor was an HLA-identical sibling for 199 patients and an unrelated volunteer in the remaining 196 patients. Children and adolescents had a comparable cumulative incidence of transplantation-related mortality, disease recurrence, and of both acute and chronic graft-versus-host disease. The 10-year probability of overall survival and event-free survival for the whole cohort of patients were 57% (95% confidence interval, 52%-62%) and 54% (95% confidence interval, 49%-59%), respectively, with no difference between children and adolescents. This study documents that adolescents with ALL in second complete remission given HSCT in pediatric centers have an outcome that does not differ from that of patients younger than 14 years of age.