PURPOSE:This study was undertaken to determine the incidence and risk factors for urinary retention after operations for benign anorectal diseases.METHODS:We reviewed 1,026 consecutive operations for benign anorectal diseases from 1989 to 1994. Risk factor analysis was done for patients undergoing hemorrhoidectomy (Group I) and other procedures (Group II) using logistic regression analysis.RESULTS:The number of procedures and urinary retention rate was as follows: 344 (34 percent) hemorrhoidectomies, 159 (2 percent) fistulotomies, 95 (5 percent) incision/drainage, 247 (4 percent) lateral internal sphincterotomy, 181 (17 percent) combinations of the above four procedures, and overall 1,026 (16 percent). In Group I, four‐quadrant excision (odds ratio, 3.3;P=0.0004), three quadrant excision (odds ratio, 2.4;P=0.003), morphine equivalents >33 (odds ratio, 1.8;P=0.01), and male gender (odds ratio, 1.7;P=0.02) were independent risk factors. In Group II, more than one operation (odds ratio, 3.0;P=0.004), older age (odds ratio, 3.1;P=0.005), intraoperative fluids (odds ratio, 2.6;P=0.03), and postoperative fluids (odds ratio, 2.7;P=0.02) were independent risk factors. Urinary obstructive symptoms for both groups and perioperative fluids for Group I were NOT independent risk factors. Hospital stay was prolonged significantly in patients with urinary retention (P=0.0001).CONCLUSIONS:Urinary retention is a common postoperative complication that increases hospital stay. It is most common after hemorrhoidectomy. Disease severity (quadrants excised and analgesia requirement for Group I and number of operations for Group II) is an important risk factor for both groups studied. Older age in Group I and perioperative fluid in Group II may be important risk factors.