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Background and Objective: Hematuria is one of the common causes of pediatric nephrology and urology diseases and is reported in 0.5-2% of children. This study was performed to determine the causes of hematuria in infants and children. Methods: This descriptive study was done on 200 infants, children and adolescents in one month to 18 year old ages with chief complaint of hematuria in Hamadan, Iran. Patients were evaluated by urinalysis, urine culture, measurement of calcium, creatinine and uric acid in random urine sample and abdominal sonography. Results: Microscopic and gross hematuria was detected in 79.5% and 20.5% of patients, respectively. Hematuria was idiopathic in 74 (37%) of patients. Urinary tract stones (18%), urinary tract infections (15.5%), hypercalciuria (13%), hyperuricosuria (10%), urinary tract anomalies (5.5%) and glomerulonephritis (1%) were diagnosed as causes of hematuria. Conclusion: In 56% of patients, hematuria was caused by three common etiologies of stone, urinary tract infections and crystalluria.