Klebsiella pneumonia is a gram negative bacillus of which it's resistant strains are a common source of nosocomial infections . The goal of this study is determination of drug sensitivity of these resistant strains, and study of causes involved in the resistant especially the presence of plasmid. Ten different strains of klebsiella pneumoniae were isolated from clinical specimens collected from microbiology laboratories of different hospitals in Kerman city,Iran. The strains were isolated from blood, urine, stool and wound infections. Genus and species of the organisms and the existence of large capsule were confirmed by bacteriological tests. The susceptibility of the strains different antibiotics were determined by disk diffusion method. The minimum inhibitory concentration(MIC) of the antibiotics was also determined. All of the isolated bacteria were resistant to ampicillin, penicillin G., amoxicillin, cloxacillin, co-trimoxazols, cephalexin cefzoline, and cephalexin. Organisms were also exhibited moderate resistance to tetracycline, chloramphenicol and erythromycin , while, they were sensitive to amikacin, gentamicin, kanamycin and rifampicin. Among them, strains 2,4,9 and 10 showed highest MIC toward cefotaxime and ceftizoxime (MIC>512 mg/L). Conjugation technique with membrane filter along with plasmid isolation of these 10 isolated strains and observation of the plasmid band on the 0.7℅ agarose gel, revealed that resistance to cefotaxime and ceftizoxime are plasmid – mediated and can transferred from K-9 to K-8 by conjugation transfer of CTX and CAZ genes to the recipient cells. Interspecies conjugation to E.coli S G20030.1 , however, was negative.