OBJECTIVE: To study the cellular activity of asparagine synthetase in different types of childhood acute lymphoblastic leukemia (ALL). METHODS: The cellular activity of asparagine synthetase was detected by HPLC-FLD and Protein measurement in 28 ALL children (7 cases of T-ALL and 21 cases of B-lymphoid lineage ALL) before chemotherapy. RESULTS: The asparagines synthetase activity levels in T-ALL children were significantly higher than those of the B-lymphoid lineage ALL patients, with the median activity level of 9.3 nM Asn/mg protein/hr vs 5.2 nM Asn/mg protein/hr (P<0.05). The distribution of the asparagine synthetase activity demonstrated a polymorphism in either T-ALL or B-lymphoid lineage ALL patients. CONCLUSIONS: The cellular activity of asparagines synthetase in ALL patients is presented with a polymorphism distribution. The asparagines synthetase activity levels in T-ALL are significantly higher than in B-lymphoid lineage ALL.