Summary Between August 1985 and April 1989, 88 patients (31 children and 57 adults) with refractory of relapsed acute lymphoblastic leukemia (ALL) were treated in a cooperative Italian trial by an induction schedule of high-dose Cytarabine (HDAra-C) plus Idarubicin (IDA). Complete remission (CR) was achieved in 52 of the 88 patients (59%); 23 patients (26%) did not respond to treatment and 13 (15%) died during induction. The CR rate was significantly affected by the WBC count at the beginning of treatment and by the duration of first CR of the patients treated at first relapse. All of the patients experienced profound myelosuppression; the median time to recovery to neutrophils > 0.5 ×10 9 /l was 15 days (range 4–40), and 14 days (range 3–50) to platelets > 50 × 10 9 /l. The most common non-hematologic side effects observed were nausea and vomiting (51%), mucositis (40%) and diarrhea (23%). Twenty-one of the 52 patients who achieved CR underwent bone marrow transplantation (BMT), 16 autologous and 5 allogeneic. Eleven patients relapsed at a median of 4 months (range 1–31) after the transplantation, and three patients died while in CR. Seven patients have been in continuous CR (CCR) for a median of 36 months (range 26–42 months). Thirty-one patients were not entered in the BMT program: for two adults it was too early, three adults died in CR and 25 patients relapsed at a median of four months (range 1–25). Only one adult is still in CCR at 33 months. The authors feel that a less toxic induction therapy followed by a consolidation regimen with non-cross resistant drugs, and by BMT, might achieve an improved control of the disease in this very high risk population.