The hemostatic toxicity of low dose L-asparaginase from Erwinia carotovora (Erwinase) has been reported to be negligible in adult patients with acute lymphoblastic leukemia (ALL); conversely, no consistent data have been obtained when Erwinase is administered at intermediate doses. We report preliminary clinical and laboratory hemostatic data from 10 adult patients with ALL treated during induction phase with intermediate doses of Erwinase (20,000 IU/m2s.c. every other day, for a total of six administrations). No thrombotic or hemorrhagic events were registered and the mean values of PT, aPTT, fibrinogen, antithrombin and D-dimer did not change during treatment. Only one patient showed a decrease of antithrombin (48% on day 8) requiring temporary suspension of Erwinase therapy. These data suggest that intermediate doses of Erwinase also have negligible hemostatic toxicity in adult patients with ALL.