L-Asparaginase enzyme that proved clinically as a treatment of Acute Lymphoblastic Leukemia (ALL). This study focused on screening, optimization, and partialypurification of L-asparaginase. Six bacteriial strains isolated from six marine samples, screening was conducted on Glucose Asparagin agar m edium supplemented with L-asparagine and phenol red as an indicator dye pH7. Pink colour around the colony was a sign of L-asparaginaseactivitywas screeened for L-asparaginase production isolates. Resulting from16S rDNA sequencing of highest L-asparaginase production isolate was identified as Halomonasalkaliantarctica. Then, it was optimized the effect of nutritionaland inoculum sizeparameters. H. alkaliantarctica recorded maximum L-asparaginase production (126.67U/min/ml) in medium supplemented with asparagine 0.1% and 1% tryptoone without carbon source at pH8 inoculated with 20% of (3.020×107CFU/ml) incubated for 48h,in shaking incubator (150rpm). The extractted enzyme of H.alkaliantarctica was partially purified using ammonium sulfate fractionation 80%.