Alvimopan is a peripherally acting mu-opioid receptor (PAM-OR) antagonist for accelerating gastrointestinal recovery after surgery. Patients undergoing open laparotomy (bowel resection, n = 418; hysterectomy, n = 197) were randomized to receive alvimopan 6 or 12 mg or placebo orally > or = 2 h before surgery and then b.i.d. until hospital discharge (up to 7 days). The primary efficacy endpoint was time to gastrointestinal (GI) recovery (measured by toleration of solid food and passage of flatus/stool; GI-3). Secondary endpoints included time to GI-2 recovery (toleration of solid food and passage of stool) and hospital discharge order written (DCO). Alvimopan did not significantly accelerate GI-3 compared with placebo [6 mg: hazard ratio (HR) = 1.20, p = 0.080; 12 mg: HR = 1.24, p = 0.038). However, after adjustment for significant covariates (sex/surgical duration), benefits were significant for both doses (6 mg: HR = 1.24, p = 0.037; 12 mg: HR = 1.26, p = 0.028). Alvimopan also significantly accelerated time to GI-2 (6 mg: HR = 1.37, p = 0.008; 12 mg: HR = 1.33, p = 0.018) and DCO (6 mg: HR = 1.31, p = 0.008; 12 mg: HR = 1.28, p = 0.015). Adverse events were similar between groups. Alvimopan (6 or 12 mg) accelerates GI recovery and is well tolerated in patients undergoing open laparotomy.