Urinary tract infection (UTI) is one of the major diseases faced by females. The main causative organism is E. coli. Though this bacterium is harmless and present in large intestine as symbiotic relationship but when it comes in contact with vagina it causes severe infection and warrants use antibiotics. As use of antibiotics leads to antibiotics resistant bacteria there is need to develop alternative medicines those may be used to fight this menace, there are several traditional medicines being used by native people and present huge scope for new drug discovery. This project work aimed at such minor research. Leaves of guava has been used traditionally to treat common fever, skin infections and others. To validate such traditional claims, it was put under the study whether this could work against E. coli bacteria. The aqueous leaf extracts of chosen guava plants Psidium guajava L. were prepared. These were studied for their antibacterial property against E. coli. P. guajava L. leaf extract showed satisfactorily results and zone of inhibition was shown in case of E. coli. 500μl P. guajava extract concentration gave best results on E. coli culture plate, showing no growth at all. For comparison with other microbes, when leaf extract was tested, no live microbes were seen in S. aureus culture broth, when P. guajava extract was added and incubated. This culture also showed decrease OD level each day, showing low microbial count. E. coli culture broth showed a little growth with the addition of extract. Pseudomonas and Klebsiella did not respond at all.