Voiding cystourethrography is commonly performed in children with prenatally diagnosed hydronephrosis, urinary tract infections, and voiding abnormalities. Voiding cystourethrography can be performed with many variations designed to optimize visualization of disease and minimize radiation exposure. The procedure should include assessment of the spine and pelvis; masses or opaque calculi; bladder capacity, contour, and emptying capability; presence and grade of reflux; and urethral appearance. Radiologists differ as to whether the patient should void prior to catheterization. Anteroposterior imaging of the bladder is performed during early filling; little or no imaging is necessary during intermediate filling. When bladder filling is complete, steep oblique images that are centered on the ureterovesical junction should be obtained. If reflux is observed, the ipsilateral renal fossa may be imaged prior to voiding. With a smaller than expected voiding volume, bladder refilling is recommended. Voiding around the catheter is also strongly recommended. In girls, one anteroposterior image of the urethra is usually sufficient; in boys, the entire urethra must be imaged. Steep oblique imaging is optimal. At the conclusion of voiding, each renal fossa should be imaged to detect reflux missed at fluoroscopy as well as other anomalies. Familiarity with these abnormalities and use of proper techniques will allow detection of most common pathologic conditions with very low radiation exposure.