Urinary retention is a condition in which impaired emptying of the bladder results in postvoid residual urine. Urinary retention has been well studied in observational studies and randomized controlled trials; data on the incidence of drug-induced urinary retention are scarce. In this article, a case of acute urinary retention developed after the use of alprazolam was discussed. A 67-year-old male underwent a prostatectomy operation for benign prostatic hyperplasia one month ago. Insomnia and dysphoria in the patient after the operation and alprazolam 1 mg/day was started. The patient started voiding problem after alprazolam treatment. No organic pathology was found to explain the table of existing urinary retention. The patient's complaints resolved completely after alprazolam treatment stopped. We should be more careful about drug-induced urinary retention. When prescribing a drug to a patient, a thorough knowledge of its mode of action, adverse effects and potential drug interactions are important in preventing drug-induced urinary retention, especially in patients who have other risk factors for urinary retention.