Backgraund & Objectives: Asymptomatic urinary tract infection (AUTI) is common in childhood and will lead to renal scars. Since the prevalence of AUTI has not been studied in Ardabil, this study set out to determine the prevalence of AUTI among primary-school children of Ardabil.

 Methods: In this descriptive-analytical study, 470 cases were selected randomly from 40,000 primary school students. The data were collected with completing a questionnaire. The cases with symptomatic urinary infection and those with discontented parents were omitted. Midstream urine was collected and sent to laboratory for analysis and culture. Colony count ≥ 100,000 CFU / ml and higher was considered as UTI and the prevalence of this complication in the samples was studied.

 Results: Of 470 subjects, 16 ones were ruled out due to urinary symptoms or parents’ discontent, and the study continued with 454 students (238 girls and 216 boys). 19 students (4.2%) had positive culture (13 girls and 6 boys). Prevalence of AUTI was 5.5% in girls and 2.8% in boys. In this study only seven cases (36.8%) had pyuria ( WBC>5).

 Conclusion: The high prevalence of AUTI specially in girls is important. Regarding the known complications of AUTI, other researches seem to be necessary to determine the causes as well as ways to prevent and treat it.