Urinary tract infection (UTI), the most common bacterial disease in childhood, is frequently associated with urinary tract anomalies (15-50%) and can induce renal scarring, which is a cause of hypertension and chronic kidney disease. Despite the high risk of renal scarring in infancy, the diagnosis may be delayed due to its nonspecific presenting symptoms; moreover, over-diagnosis is frequent due to the contamination of urine samples. The delay in diagnosis and treatment may induce sepsis or renal scar, while over-diagnosis is responsible for unnecessary antibiotic treatment and costly urinary imaging studies. UTI guidelines have been ever-changing for the past three decades, but some controversial issues remain. This article is a revision of the previous KSPN (Korean Society of Pediatric Nephrology) guideline and addresses the recent controversies concerning childhood UTI.