Toxin extract affects Neutrophils and macrophages, which are phagocytic cells. A total of (180) samples, (50) urine and (130) peripheral blood have been obtained from leukemia patients referred to Medical city/ Baghdad Teaching Hospital/ Hematology center; all patients enrolled in this study were diagnosed by the physician according to clinical presentation and laboratory findings as leukemic patients. Investigate the role of Enterobacter cloacae toxins on phagocytic activity/THP-1cells and epithelial line/HBL-100 cells. THP-1 and HBL-100 cells have been kept in RPMI-1640 that have been supplemented by (10%) of the fetal bovine serum (100µg/mL) of the streptomycin and 100units/mL of the penicillin. The cells have been passaged with the use of the Trypsin-EDTA that has been re-seeded at a confluence of 80% twice every week, and then it has been incubated afterward at a temperature of (37C°). The results of toxin extract from Enterobacter cloacae revealed that (22) fraction/toxins were taken from (11) bacterial samples; these toxins were separated by gel electrophoresis for protein. (18) samples were positive results for gel electrophoresis of protein according to molecular weight: (13.3 KD for α-hemolysin), (70.5 KD for thiol), (75 KD for enterotoxin). This study demonstrates the cytotoxic activity of E. cloacae toxin by using tissue culture through their effect on suppressing the growth of "THP-1 cells" and HBL-100 cells". Keywords. Tissue culture; Toxin; THP-1 cells; HBL-100 cells; Enterobacter cloacae; Leukemia patients.