Cefepime is a semi-synthetic, broad spectrum, cephalosporin antibiotic for parenteral administration. Cefepime is a bactericidal agent that acts by inhibition of bacterial cell wall synthesis. It has a broad spectrum of In vitro activity against wide range of gram positive and gram-negative bacteria. In a prospective study 100 of bacterial species were studied by a susceptibility test by disk diffusion (Kirby–Bauer) in Tabriz Pediatric Medical Center. This study compares inhibitory effect of cefepime with that of Penicillin, Chloramphenicol, Ampicillin, Cotrimoxazol, Gentamycin, Cefotaxime, Vancomycin, Ciprofloxacin, Ceftriaxone, Amikacin and Erythromycin on Klebsiella pneumoniae, Staphylococci coagulase negative, Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, Salmonella Sp, Enterobacter cloacae, Proteus mirabilis, Acinetobacter Sp and Streptococcus Sp. During 6 month in 100 bacterial strains (clinical isolated), the resistance to cefepime on Pseudomonas aeroginosa (100%), Klebsiella pneumoniae (46%), Staphylococcus aureus (40%), Staphylococci coagulase negative (40%), Enterobacter cloacae (40%), Acintobacter sp (30%), Proteus mirabilis (20%), E.coli (6%), Streptococcus non group A (0%) Seratia marcescens (0%), Salmonella non typhi (0%) were respectively. The In vitro inhibitory effect of cefepime on Pseudomonas aeroginosa was found to be less than other bacteria, Whereas Streptococcus SP, Seratia marcescens, Salmonella and E.coli was more sensitive to cefepime. The inhibitory effect of cefepime on bacterial isolations and it’s comparison with other antibiotics demonstrate a broad spectrum of activity of cefepime. And the resistant bacterial strains were developed against this antibiotic in this area.