We evaluated the role of BMT in a cohort of 56 children with ALL relapsing after uniform initial treatment protocols in a single institution between 1990 and 1997. The patients were commenced on a single intensive chemotherapy regimen. All patients with a matched family donor (MFD) were recommended to receive BMT. The outcome was significantly better for patients with a MFD. The overall survival at 8 years was 60.0% (95% CI 35.7-77.6%) and 13.5% (95% CI 4.0-28.6%) for patients with and without MFDs (log-rank chi = 7.50 P = 0.0062). The event-free survival at 8 years was 55.0% (95% CI 11.1-31.3%) and 9.2% (95% CI 2.0-23.3%) for patients with and without MFDs (log-rank chi = 8.87 P = 0.0029). Multivariate analysis confirmed the survival advantage of BMT. There was no statistically significant difference in survival for patients initially relapsing within 3 years of first remission compared to children relapsing beyond 3 years. BMT provides a clear survival advantage for children following their first relapse of ALL. We recommend BMT for all children following first relapse of ALL if a MFD is available.