In this prospective study we compared local with spinal anesthesia for anorectal surgical procedures with regard to pain control, recovery time before unassisted ambulation, incidence of postoperative complications, length of hospital stay, and cost effectiveness in 80 consecutive patients. Patients were allocated in two groups: group 1 (n = 52) received local anesthesia, and group 2 (n = 28) had spinal anesthesia. There were no intraoperative complications related to the anesthetic technique, and there was no difference between groups in the number of doses of narcotics required to control postoperative pain (1.2 +/- 1.5 vs 1.8 +/- 1.7 in group 1 and 2 respectively, P > 0.05). Recovery time before unassisted ambulation was significantly longer in group 2 (139 +/- 96 minutes in group 2 vs 82 +/- 62 minutes in group 1, P < 0.05). There were 21/52 complications in group 1 in contrast to 21/28 in group 2, (P < 0.05). There was no difference between groups in the postoperative incidence of nausea, vomiting, headache, weakness, and constipation; however, the incidence of postoperative urinary retention was significantly higher in group 2 (5/52 in group 1 vs 9/28 in group 2, P < 0.05). As a result of urinary retention, more patients in group 2 required overnight hospitalization (12/52 in group 1 vs 21/28 in group 2, P < 0.05). Patients in group 2 required 36 hospital days in contrast to 21 days for patients in group 1, P < 0.05. The difference in hospital days resulted in $18,000 greater cost for patients in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)