Rupture or contrast extravasation of urinary bladder after voiding cystourethrography(VCUG) was a very rare complication which occurred in neurogenic or unused bladder. Only one case of bladder extravasation was reported in a girl with normal bladder function. Case: A 18 month-old boy presented with recurrent E. Coli urinary tract infection and was evaluated with isotope VCUG, which was failed to catheter insertion. Two days later, isotope VCUG was repeated with difficult catheter insertion. Two hours after isotope VCUG, gross hematuria and anuria developed, and abdominal distension was followed. Bladder rupture was diagnosed by abdominal sonography and computerized tomography. He was treated with simple closure and suprapubic catheter drainage.