PATIENTS' INABILITY to urinate represents one of the most common genitourinary problems encountered by emergency physicians. Although acute urinary retention is not usually life threatening, the disorder produces considerable discomfort for the patient, may account for significant morbidity, or may signal a more serious underlying disease process. Urinary retention necessitates accurate recognition and prompt bladder drainage, not only to alleviate symptoms, but also to prevent the development of dangerous sequelae, such as urosepsis and obstructive nephropathy.