Bladder ultrasound is noninvasive, readily accessible, and easy to use. It has been extensively investigated as a possible substitution for some of the more common invasive modalities used to evaluate the bladder, namely cystoscopy and cystography. Its broad range of applications includes determination of the presence and volume of postvoid residual urine, assessment of suspected bladder stones, diverticula, and other lesions, evaluation of the bladder neck for hypermobility in women suspected of stress incontinence, and assessment of pediatric patients who have posterior urethral valves, ureteroceles, and, more recently, vesicoureteral reflux.