There are many causes of acute urinary retention. Reported here is a case of one of the more rare causes: herpes zoster. Fewer than 70 cases have been reported in the literature since 1890. In the present clinical environment where many patients are immunocompromised, reports of herpes zoster and its sequelae are no longer thought of as anecdotal. The virus may interrupt the detrusor reflex due to involvement of the sacral dorsal root ganglia. Urinary retention with sensory loss of both bladder and rectum as well as flaccid paralysis of the detrusor can develop in patients with herpes zoster. Fortunately, the outcome of this process is benign and full recovery of the detrusor is likely.