Background: Asymptomatic bacteriuria is the significant presence of bacteria in the urine of an individual without symptoms. In pregnancy, the apparent reduction in immunity of pregnant women tends to encourage the growth of pathogens. Aim: This study was carried out to determine the prevalence of asymptomatic bacteriuria in pregnant women attending a primary health centre in Benin City, Nigeria. Materials and Methods: A total of 1,228 pregnant women were recruited for this study. All subjects were clinically identified to have no signs and symptoms of UTI. Clean catch midstream urine sample was collected from each patient into sterile universal container. The urine samples were examined microscopically and by cultural method. Identification of isolates was by standard microbiological technique. Result: A total of 556 (45.3%) were positive for significant bacteriuria. There was a significant difference in the prevalence of asymptomatic bacteriuria with respect to age (P < 0.0001). Trimester did not show any significant difference (P = 0.2006) in the prevalence of asymptomatic bacteriuria. Escherichia coli was the most predominant organism followed closely by Staphylococcus aureus. Ciprofloxacin, Ceftriaxone and Augmentin were found to be the most effective antibiotics against the urinary isolates. Conclusion: Asymptomatic bacteriuria is not uncommon among antenatal patients in the population studied. Routine urine cultural test should be carried out on all antenatal patients in order to identify any unsuspecting infection. This measure will go a long way in reducing maternal and obstetric complications associated with pregnancy.