Urinary tract bacterial infections are common in women. Moreover, they tend to recur throughout life and in the same relatively small group of women. In most cases, bladder and renal infections are asymptomatic and manifest by demonstrating coincidental bacteriuria. In some instances, however, especially with frequent sexual activity, pregnancy, stone disease, or diabetes, symptomatic cystitis or pyelonephritis develops and antimicrobial therapy is indicated. In most cases, cystitis is easily managed with minimal morbidity. When acute pyelonephritis develops in an otherwise healthy woman, however, consideration for ureteral obstruction is entertained. If her clinical response to proper therapy is not optimal, then imaging studies are indicated. Pregnancy is a common cause of obstructive uropathy, and severe renal infections are relatively common. Because they usually arise from preexisting covert bacteriuria, experts recommend screening and eradication of these silent infections as a routine prenatal practice.