This is a multicenter, randomized, controlled study in women who are having elective open abdominal surgery with general anesthesia and who are expected to need patient-controlled analgesia (PCA) after surgery. The primary objective is to assess the effect of rolapitant in the prevention of postoperative nausea and vomiting as measured by the prevention of vomiting in the first 24 hours after surgery. Participation in the study may last up to 3 months. The total duration of the study will be approximately 36 weeks.

Inclusion Criteria:

• Women aged 18 years or older of any race with an American Society of Anesthesiologists (ASA) physical status of I to III who are scheduled to undergo elective open abdominal surgery under general anesthesia.
• Women whose postoperative hospitalization is expected to last at least 24 hours
• Women expected to require postoperative intravenous opioid PCA.
• Women whose surgery is expected to require at least 1 hour, but not more than 4 hours, of general anesthesia using the regimen defined in this protocol.
• Women of childbearing potential who have a negative pregnancy test or women who have been surgically sterilized or are postmenopausal.

Exclusion Criteria:

• Women with clinically significant or unstable cardiac, respiratory, hepatic, renal, or other major organ system disease.
• Women with a known hypersensitivity to ondansetron (or any other 5-HT3 antagonist), to any agent that is part of the anesthesia regimen, or to other medications to be administered under this protocol.
• Women who are scheduled to undergo certain types of surgery.
• Women who are breastfeeding.
• Women who have retching/vomiting or moderate or severe nausea in the 24 hours prior to surgery or suffer from chronic nausea and/or vomiting.
• Women with a body mass index (BMI) >40.
• Women who have participated in a clinical trial of an investigational drug within 30 days prior to drug administration.