The present study was aimed to determine the prevalence of urinary tract infection among the pregnant women with lower abdominal pain and its aetiological micro-organism. Cross sectional study was done at Mount meru hospital laboratory, Arusha, Tanzania. 225 pregnant women attending an antenatal clinic in Levolosi hospital (Arusha, Tazania) were enrolled. To diagnose urinary tract infection in the enrolled participants, mid stream urine was collected and culture on Macconkey agar media and blood agar media. Urine analysis was done using dipstick test, urine microscopy and biochemical tests. The prevalence of urinary tract infection was found to be 31.6%. High incidence of infection was found in 33-40 years age group (41.6%). The incidence of infection was high in the third trimester of pregnancy compared to first and second trimester. The prevalence of infection is more in participants who had past history of infection. The bacterial pathogens isolated include E.coli (40.8%), Staphylococcus species (30.0%), Klebsiella species (14.1%), Proteus species (11.3%), Citrobacter species (1.4%) and Enterobacter species (1.4%). Diagnosis of urinary tract infection in pregnant women during all antenatal visits should be considered a vital care in the community. This helps to keep away from complications in pregnancy at an early stage.