UTIs occur quite frequently among adolescent females. In the vast majority of these patients, UTIs are uncomplicated infections and are not suggestive of underlying anatomic abnormality of the urinary tract. A UTI in an adolescent female is suggestive, however, of sexual debut. A small number of adolescent males suffer from UTI annually; in at least half of such cases, there is likewise no underlying urinary anomaly. Because of the symptomatic overlap and high prevalence of STI in adolescents, the clinician must have a high index of suspicion for STI in any adolescent presenting with urinary symptoms.