BACKGROUND: It has been known that bed rest after spinal anesthesia for benign anorectal surgery helps to reduce the incidence of postdural puncture headache, but the bed rest position is thought to have a negative effect on urinary retention, as a result of anxiety, anal distention, bladder distention and pain-induced reflex inhibition of the urinary bladder detrusor muscle. We investigate the effect of early ambulation after spinal anesthesia on postdural puncture headache and on urinary retention compared with bed rest for 24 hours. METHODS: One hundred and fifty-three ASA Physical Status I patients received spinal anesthesia for scheduled benign anorectal surgery. We applied hyperbaric 0.5% tetracaine 6 mg (1.2 ml) using 25 gauge Quincke needles with the cutting bevel parallel to the dural fibers at the patients' sitting position. All patients were randomly divided into an early ambulation group or bed rest group. We investigated the incidence of urinary retention and headache. The duration of operation, the perioperative intravenous fluid volume, surgical technique and postoperative pain regimen were standardized. RESULTS: The incidence of urinary retention in the early ambulation group (16/75, 21.3%) was lower than that in bed rest group (32/78, 41.0%). There was no difference in any parameters between the two groups. CONCLUSIONS: To reduce the incidence of urinary retention, early ambulation after spinal anesthesia for benign anorectal surgery is recommended over bed rest with no increase in the incidence of postdural puncture headache.