Fifty-seven patients aged < 55 years with acute lymphoblastic leukemia (ALL) in second or third bone marrow (BM) relapse or refractory to first-line therapy were enrolled in an Italian cooperative study. The ALL R-87 protocol included idarubicin (IDA) plus intermediate dose cytarabine (IDARA-C) and Prednisone (PDN) as induction, followed by a consolidation phase and BMT. Complete remission (CR) was achieved in 41/57 patients (72%). The CR rate was significantly higher in patients aged < 15 years at diagnosis and at time of treatment compared to those aged > or = 15 (84% vs 50%, p=0.01 and 85% vs 54%, p = 0.02, respectively). Nineteen of 41 responders (46.3%) underwent bone marrow transplant (BMT) (10 autologous and 9 allogeneic). The estimated probabilities of event free survival (EFS +/- SE) and survival +/- SE at 6 years were 0.13 +/- 0.05 and 0.20 +/- 0.06, respectively, for all enrolled patients. Univariate analysis showed that children had a better EFS rate compared to adults (0.16 +/- 0.07 vs 0.08 +/- 0.07, p = 0.014). The estimated probability of disease free survival (DFS +/- SE) at 6 years was 0.18 +/- 0.07 for all responders. No differences in DFS were observed between patients submitted to allogeneic or autologous BMT (0.33 +/- 0.16 vs 0.25 +/- 0.15). Among patients treated in second or third relapse, a first CR length > or = 48 months favorably influenced both DFS (p = 0.014) and EFS (p = 0.018). Our results show the efficacy of the intermediate dose ARA-C plus IDA schedule for high risk adult and childhood ALL patients. No differences in disease outcome were observed between allogeneic and autologous BMT.