In this study, the bacteria from sputum specimens of patients with respiratory tract infections were isolated in   IbnSina Teaching Hospital, Mosul city, Iraq.  The bacteria  were subjected to phenotypic and biochemical tests necessary for identification. Twenty five isolates of six different bacterial species were obtained, they are : Staphylococcus aureus, Streptococcus pneumonia, Moraxella cattarhalis, Escherichia coli, Klebsiella pnuemoniae and Pseudomona saeruginosa with ratios (64%, 12%, 8%, 8%, 4% and 4% ) respectively. The sensitivity and resistance of these isolates to 12 antibiotic were studied, where the Gentamycin appear to be more effective on most of the isolates while all the isolates showed  resistance to Nalidixic acid with 100% percent . Also, Plasmid DNA content showed different sizes of DNA bands in four types of these isolates.