Background: Urinary tract infections are the most common medicalcomplication of pregnancy. Asymptomatic bacteriuria is the mostprevalent of these infections and it is defined as, the finding of greater than(100,000) colony forming units per mL of urine of a single pathogen intwo consecutive, midstream, clean catch urine specimens or onecatheterization specimen.Objectives: The aim of this work is to assess the prevalence ofasymptomatic bacteriuria in primi gravid patient during mid trimester inthose attending Kasr El Aini Hospital obstetric outpatient clinic from Julyto December 2008.Patients and Methods: This study includes 100 women, inclusioncriteria: primigravida, age from (15-30) and mid trimester pregnancy (14-25 weeks), exclusion criteria: women known to be diabetic, women whoare immuncompromised as in long term corticosteroid therapy, womenusing vaginal douches, any type of vaginal bleeding, women already onantibiotic therapy. All patients underwent the following:1. Full history taking2. Physical examination3. Investigation: Ultrasonography or sonicade to ensure fetal life Laboratory investigations: hemoglobin levels, urine culture and ABsensitivity.Results: Among the 100 women included in this study, 8 had bacteriuriagiving prevalence of 8%. In this study previous history of urinary tractinfection was found to be an important risk factor as there is a highstatistical significant difference between bacteriuric and non bacteriuricwomen as regard history of previous UTI. The prevalence ofasymptomatic bacteruria was increased in anemic patients and patientsfrom low socioeconomic class.Conclusion: It is important that pregnant women are screened forasymptomatic bacteriuria at the first antenatal visit.