Allogeneic bone marrow transplant (BMT) with an MRD in complete remission (CR)1 is the preferred treatment for children with Philadelphia-positive (Ph(+)) ALL. The role of MUD BMT in CR1 is still controversial. We compared the outcomes of two treatment strategies: BMT using an MRD or MUD vs chemotherapy in children with Ph(+) ALL in CR1. In total, 21 children were treated from 1985 to 2001. In all, 10 received chemotherapy and 11 received allogeneic BMT: four MRD, seven MUD. In the MRD group, one relapsed 12 months after BMT and died; the remaining three are long-term event-free survivors (median follow-up, 6.1 years). In the MUD group four died; the remaining three are long-term event-free survivors (median follow-up, 7.2 years). The 4-year event-free survival (EFS) for the BMT group was 53+/-15%. In the chemotherapy group, seven relapsed after a median period of 12.5 months and three remain in continuous CR (median follow-up, 2.4 years). Four chemotherapy patients received CR2 transplants; all died. The 4-year EFS for the chemotherapy and MUD groups was 33+/-17 and 35.7+/-20%, respectively. This difference was not statistically significant. We continue to support treating children with Ph(+) ALL with MRD BMT in CR1. The effectiveness of MUD BMT vs chemotherapy merits further study.