The t(2;5)(p23;q35) was detected in 9 of the 18 cases of large-cell lymphoma with an abnormal karyotype among 115 children with large-cell lymphoma treated at St Jude Children's Research Hospital from 1975 to 1993. When the cases containing the t(2;5) were classified according to the National Cancer Institute Working Formulation, 7 were large-cell, immunoblastic and 2 were diffuse large cell; according to the Kiel classification system, 6 were anaplastic large cell, 2 immunoblastic, and 1 centroblastic. CD30 expression was documented in 6 of 8 cases tested. All patients had nodal disease and 6 had extranodal involvement (bone in 4 cases and skin in 3). Eight of nine had advanced disease at diagnosis (stage Ill in 7 and stage IV in 1). Complete remission (CR) was attained in all patients and 6 remain in first CR for 19+ to 97+ months. Three relapsed, but successfully obtained second remissions; 2 are 58+ and 80+ months after retrieval therapy for local recurrences, and 1 patient died of recurrent disease. The t(2;5)(p23;q35) is associated with, but not limited to, anaplastic histology, a CD30+ T-cell phenotype, advanced stage disease with nodal (+/- extranodal) involvement, and chemosensitivity at diagnosis and relapse.