This study compares the inhibitory effect of ceftizoxime with that of penicillin G, chloramphenicol, cephalothin, cephalexin and cefzoline on Klebsiella pneumoniae, Proteus mirabilis, pseudomonas ruginosa, staphylococcus aureus, staphylococcus epidermidis, staphylococcus saprophyticus and Escherichia coli. The in vitro inhibitory effect of ceftizoxime on P. mirabilis, P. Aeruginosa, S.prophyticus and E.coli was found to be more than other bacteria. Whereas S, aureus was more nsitive to cephalothin in comparison with ceftizoxime. The minimal inhibitory and lethal concentration MIC & MBC of ceftizoxime on bacterial isolated was determined by tube dilution method. The lowest of drug was needed to inhibit / kill P. Mirabilis and K. Pneumoniae, whereas the highest level was found for P. Aeruginose. The inhibitory effect of ceftizoxime on the bacterial isolates and it's comparison with other antibiotic tested, demonstrates the broad spectrum of activity of ceftizoxime and the resistant bacterial strains were not developed against this antibiotic in the area so far.