Infections of the lower urinary tract affect 10% to 20% of all women, among whom a substantial proportion go on to experience recurrent infections. Bacterial virulence factors, particularly those enhancing mucosal adherence, are important in the pathogenesis of urinary tract infection. The use of a diaphragm with spermicides predisposes to urinary tract infection, most likely through alterations of the normal vaginal flora. Urine microscopy is the most accurate rapid office test for urinary tract infection. Automated and dipstick techniques yield slightly lower sensitivity and specificity. Recent treatment trials indicate that 3-day therapy for uncomplicated lower urinary tract infection provides an optimal balance between efficacy and adverse effects when compared with single-dose therapy or treatment for 7 to 10 days. Antibiotic prophylaxis is an important strategy in treating recurrent infections and is effective for periods as long as 5 years without undue emergence of resistant bacterial strains. Interstitial cystitis remains an elusive entity without definite diagnostic criteria or clearly effective therapy.