During A-ALL induction treatment, HD-ara-C (2.5 g/m2 IV, day 1), does not produce any beneficial effect, whereas the hematologic toxicity is increased. A 3-month consolidation phase comprising intermittent MTX, ara-C and 6-TG is not significantly affecting either DFI or survival in A-ALL. The association of HD-ara-C and m-AMSA appears to be a promising salvage therapy for the 20% A-ALL refractory to first induction therapy. The quality of autologous bone marrow graft, harvested after HD-ara-C, seems to be impaired as suggested by a delayed recovery of PMN and platelets. HD-ara-C (3 g/m2 X N) given the days before cyclophosphamide and TBI as conditioning treatment for BMT does not seem to induce prohibitory additional toxicity. Whether HD-ara-C was given four to six times or eight to 12 times gave no significant difference in early toxicity.