INTRODUCTION: Robotic assisted laparoscopic radical prostatectomy (RALP) is a common treatment for localized prostate cancer. Despite a primary advantage of improved postoperative pain, patients undergoing RALP still experience discomfort. Belladonna, containing the muscarinic receptor antagonists atropine and scopolamine, in combination with opium as a rectal suppository (B & O) may improve post-RALP pain. This study evaluates whether a single preoperative B & O results in decreased postoperative patient-reported pain and analgesic requirements. MATERIALS AND METHODS: Patients undergoing RALP at Virginia Mason Medical Center between November 2008 and July 2009 were offered the opportunity to enter a randomized, double-blind, placebo-controlled trial. Exclusion criteria included: glaucoma, bronchial asthma, convulsive disorders, chronic pain, chronic use of analgesics, or a history of alcohol or opioid dependency. Surgeons were blinded to suppository placement which was administered after induction of anesthesia. All patients underwent a standardized anesthesia regimen. Postoperative pain was assessed by a visual analog scale (VAS) and postoperative narcotic use was calculated in intravenous morphine equivalents. RESULTS: Ninety-nine patients were included in the analysis. The B & O and control groups were not significantly different in terms of age, body mass index, operative time, nerve sparing status or prostatic volume. Postoperative pain was significantly improved during the first two postoperative hours in the B & O group. Similarly, 24-hour morphine consumption was significantly lower in patients who received a B & O. No adverse effects secondary to suppository placement were identified. CONCLUSION: Preoperative administration of B & O suppository results in significantly decreased postoperative pain and 24-hour morphine consumption in patients undergoing RALP.