Urinary tract infection is a complex situation and it is not a specific entity. Infection of the urinary tract ranges from asymptomatic bacteriuria through cystitis, urethritis to pyelonephritis. Even in asymptomatic bacteriuria the bacterial counts may exceed more than 105/ml. Pyuria is commonly seen in urinary tract infection the number of pus cells seen under the microscope depends upon the way the specimen is obtained, the urine flow rate, the intensity of tissue reaction, the volume of urine, time and speed of centrifugation, the volume of the resuspension. Urinary tract infection are extremely common in women, the incidence being in the range of 10 to 20 percent. The most common mode of infection is ascending type wherein microorganisms present in the host’s own intestinal tract produce surface contamination of the urethra and migrate upward through the urinary passages from the urethra, bladder, and ureters to the kidneys.