UTIs are common in children. They may present with a range of severity from cystitis to febrile UTI or pyelonephritis. The presentation may be vague and have nonspecific symptoms. Therefore, a UTI should be considered in all children with a fever in whom other sources have been excluded. Treatment depends on the age, location of infection, and degree of illness in the child. Sick children and infants less than 3 months should be treated as inpatients, and healthy children and older infants may be treated as outpatients. Urinalysis provides presumptive evidence of infection, whereas urine culture is definitive. Close follow-up and outpatient evaluations are needed to prevent long-term consequences of infection.