Within Spanish hospitals that do routinely measure asparaginase levels, there was consistency regarding the timing of levels, with 84.2% of participants reporting day 7 for pegylated asparaginase, 48 h for Erwinia, and 14 days in case of maintenance with pegylated asparaginase (in the intermediate risk of the National ALL protocol, there is a pegylated asparaginase intensification every 2 weeks). Here, ASPG is linked to acute lymphoblastic leukemia.