Approximately five percent of pediatric acute lymphoblastic leukemias (ALL) contain a translocation (9;22)(q34;q11) which results in rearrangement of the bcr and abl genes. At a median follow-up of 5 years, we assessed the prognostic implications of translocation (9;22) in 434 children receiving intensive treatment for ALL. Four-year event-free and overall survivals were only 0% and 20%, respectively, in 15 children with translocation (9;22), but were 81% and 89%, respectively, in 419 children lacking translocation (9;22) (P < 0.001). Based on these findings, we recommend very intensive treatment approaches for all children with translocation (9;22)-positive ALL.