BACKGROUND: In previous our retrospective study, we concluded that administered fluid volume, duration of operation, operative procedures and anesthetic techniques were the major factors of postoperative urinary retention. However, the administered fluid volume, age, types and duration of the operation confined to hemorrhoidectomy was questioned as a precipitating factor. The high retention rate in spinal anesthesia is also questioned. METHODS: We investigated these possible precipitating factors of urinary retention in healthy patients (n=154) undergoing hemorrhoidectomy. The patients were randomly divided into three different anesthetic techniques: caudal (2% lidocaine 300 mg with 1 : 200,000 epinephrine), spinal (0.5% tetracaine 5 mg with epinephrine 0.1 mg or 5% lidocaine 40 mg) and general (enflurane, N2O, vecuronium). Urinary retentin was searched according to above factors following surgery. RESULTS: The overall urinary retention rate was 46.1%. The retention rate in patients with spinal anesthesia was higher than that in those with other anesthetic techniques (p<0.05). There was no significant difference between patients with lidocaine and tetracaine spinal anesthesia in urinary retention rate. The administered fluid volume in patients with urinary retention was significantly higher than that of patients without retention (p<0.05). Age, duration and types of hemorrhoidectomy did not significantly affect urinary retention rate. CONCLUSIONS: Restriction of fluid administration and avoidance of spinal anesthesia are necessary in reducing postoperative urinary retention following hemorrhoidectomy.