OBJECTIVES: This study aimed to compare the effect of periurethral infiltration of bupivacaine versus normal saline on postoperative voiding function and pain in patients undergoing retropubic midurethral sling. METHODS: A randomized double-blind placebo-controlled study was performed at the University of Massachusetts from March 2012 to June 2015. Ninety patients were randomized to receive 0.5% bupivacaine with epinephrine or normal saline with epinephrine solution for periurethral hydrodissection. Postoperative pain was assessed at 2 to 3 and 6 to 7 hours using a visual analog scale. Voiding function was determined by the proportion of subjects passing or failing a voiding trial. Descriptive statistics and percentages were used to compare the rate of voiding dysfunction. A logistic regression analysis was performed adjusting for possible covariates. RESULTS: Ninety subjects enrolled and 45 were randomized to each group. Thirty-nine subjects received the normal saline and 41 received bupivacaine. The remaining 10 withdrew before the procedure. Pain scores at 2 to 3 hours did not differ between the groups (P = 0.837), but at 6 to 7 hours, patients who received bupivacaine had less pain (P = 0.028). There was no difference in voiding dysfunction between the study and placebo groups (17.9% and 24.4%, respectively; P = 0.481). Because of the unavailability of indigo carmine midway through the study, 36 of 80 subjects received preoperative phenazopyridine for the assessment of ureteral patency. Three (8%) of these subjects failed their voiding trial compared with 19 (30%) of the patients who did not receive phenazopyridine (P = 0.010). CONCLUSIONS: The use of bupivacaine did not affect postoperative voiding function but had lower pain scores at 6 to 7 hours postoperatively. Preoperative phenazopyridine may reduce postoperative urinary retention.