UTI is the most common infection in all ages and urinary catheters especially long-term catheterization are important predisposing factors of UTI. Urinary catheters are used in different hospital wards as a complementary curative method for the patients who are undergone various surgical procedures, such as: cesarean, hysterectomy, laparotomy, etc and they who are unable to control their voided urine. 226 urine specimens were collected from 119 catheterized patients which had been hospitalized in seven wards of Razi and Golestan hospitals in Ahwas city. At least two urine specimens were collected from each patient, before and after the insertion of the catheter. All of the specimens were inoculated to suitable Media, after transportation to the Microbiology Lab. Isolated colonies were identified and their resistance patterns were determined by the standard disk diffusion method (Kirby –Bauer procedure) to 8 different antibiotics. 38 cases (43.6%) out of 87 patients showed Bacteriuria in the end of catheterization. They had no bacteriuria symptoms or sign before the catheterization. The most cases (28.9%) of bacteriuria occured in 30-39 years group and the lowest cases (2.6 %) of them occured in 60-69 years group. Out of 50 bacterial strains isolated from urine cultures, E.coil (with 17 cases) was the highest (34%) and Staphylococcus aureus, Klebsiella pneumoniae, Edwardsiella tarda, Enterobacter sakazakii (with 2% for each) were the lowest cases. E.coli, Enterobacter and Kl. rhinoscleromatis, showed the most resistance to Ampicillin, Penicillin, Cephalexin, and the lowest rate to Nalidixic acid, Gentamicin and Nitrofurantoin. Staphylococcus epidermidis isolates, also, showed the most resistance (100%) to Penicillin and Ampicillin, and the lowest rate to Gentamicin (with 66.7%), Cotrimoxazol and Nitrofurantoin (with 50%). The results of this study suggested that catheterization, especially long- term catheterization causes the rise of urinary infections and so it is recommended that urinary catheters be avoided whenever possible.