Background: Campylobacter spp. that have been frequently isolated from livestock's, meat and chicken cause acute diarrhea in developed countries. This study was conducted to screen the cases of diarrhea at two children hospitals in Tehran to detect the bactriologically confirmed cases of campylobacteriosis and to determine the rate of causative agents to different antimicrobial drugs.Methods: Five-hundred fecal samples of patients with acute diarrhea were received from two children hospitals, Children Medical Center and Mofid Hospitals during October 2003 and October 2004. Samples were received in Cary Blair transport medium to the Food Borne Disease Laboratory. They were then plated either directly on Brucella agar containing supplement or enriched in Preston broth for subsequent plating. The inoculated plates were incubated in microaerophilic condition for 48 hours. Drug susceptibility testing was performed using disk diffusion agar.Results: During the study period, 39 campylobacter strains were isolated (7.8%). Campylobacter jejuni was the dominant species isolated from the clinical specimen (75.7%). The rates of susceptibilities to different antibiotics were as follows: gentamicin, imipenem and colistin (100%), streptomycin and chloramphenicol (97%), neomycin (94.1%), ampicillin (88.2%), erythromycin (85.2%), tetracycline (70.5%), cefotaxime (58.8%), ciprofloxacin (20.5), carbenicillin (50%) ceftazidime (32.2%). All isolates were resistant to cephalexin.Conclusion: The frequency of recovery (7.8%) from children with diarrhea shows that the organism could be one of the major etiologic factors of diarrhea among children in Tehran. The high rate of resistance to quinolone warrants further for the possible reasons.