Background and Objective: Urinary tract infection (UTI) is one of the most common bacterial infections in the childhood which could result in chronic renal failure and hypertension. Antibiotic resistance is increasing due to widely using of antibiotics. The aim of this study was to determine the MIC of antibiotics which are using in the treatment of UTI in children by E-test. Materials and Methods: In this descriptive study, 87 E.coli strains were isolated from the urine samples of the patients with UTI. E.coli antimicrobial susceptibility was determined using E-test. The MIC for each antibiotic was determined and classified using NCCLS criteria. Results: Eighty seven urine samples were collected from 57 girls (65.5%) and 30 boys (34.5%). The mean age for girls was 61 months and for boys was 41 months (p=0.015). The MIC (50 and 90 percentiles) for each antibiotic was as fallow: Ampicillin (256, 256), Amikacin (1/5, 4/8), Gentamycin (0.38, 32), Nalidixic Acid (1/5, 256), Ceftriaxon (0.023, 32), Cefixim (0.19, 256) and Trimethoprim-Sulfamethoxazole (32, 32). The antibiotic susceptibility rate for each antibiotic was as fallow: Ampicillin (21.8%), Amikacin (92%), Gentamycin (75.5%), Nalidixic Acid (64/4%), Ceftriaxon (72/4%), Cefixim (65/5%) and Trimethoprim-Sulfamethoxazole (41/4%). Conclusion: This study showed that the antibiotic resistance of E.coli was very high. Due to increasing rate of E.coli resistance to Ampicillin and Cotrimoxasole in children, it is better to reconsider the empirical therapy with these antibiotics. Since in this study a lower resistance rate of E.coli was observed for Amikacin and Gentamycin therefore, we could suggest these antibiotics as alternatives in the treatment of children with urinary tract infection.