OBJECTIVES The aim of this study was to determine whether the use of a preoperative transdermal scopolamine (TDS) patch for postoperative nausea and vomiting prophylaxis affects the success of a voiding trial after a transobturator tape sling procedure. METHODS This study is a retrospective cohort study of adult women who underwent a transobturator tape sling procedure without concomitant procedures from February 1, 2009 through August 1, 2010. The exposed group included all eligible women who received a preoperative TDS patch. For each exposed woman, we selected the next 2 consecutive eligible women who did not receive a TDS patch to be included in the unexposed group. The primary outcome was postoperative voiding trial failure. RESULTS We identified 35 women who met eligibility criteria and used a preoperative TDS patch, and included 70 women who did not use a preoperative TDS. A significantly higher proportion of women in the TDS patch group (54.3%) failed their voiding trial than in the group that did not receive TDS (7.1%, P ≤ 0.001). A history of an incontinence procedure, older age, and higher body mass index strengthened the association between TDS patch and voiding trial failure. The adjusted model yielded a risk ratio for voiding trial failure of 13.8 (95% confidence interval, 5.2-36.5) for women who received TDS patch compared with those who did not. CONCLUSIONS The results of this study demonstrate that use of TDS patches for postoperative nausea and vomiting prophylaxis may negatively affect the success of voiding trials after transobturator tape sling procedures.