The aim of this study is to compare the possible efficacy of ondansetron and gabapentin on postoperative nausea and vomiting in patient with morbid obesity who will undergo laparoscopic sleeve gastrectomy.

This study will be a double blind randomized, controlled, parallel, study. A total of1 00 morbidly obese patients who will be scheduled for sleeve gastrectomy will be included in the study. The patients will be selected from those attending Gastrointestinal and Laparoscopic Surgery Unit, General Surgery Department, Tanta University Hospital, Tanta, Egypt. The participants will be randomized into two groups by closed envelop method,

Inclusion Criteria:

• Both male and female patients will be included.
• Morbidly obese patients scheduled for sleeve gastrectomy with BMI ≥35 kg/m2 with the presence of comorbidity such as hypertension, arthritis, and diabetes.
• Morbidly obese patients scheduled for sleeve gastrectomy with BMI ≥ 40 kg/m2 without comorbidity.
• Patients fit for anesthesia and surgery.

Exclusion Criteria:

• - Patients with BMI >55 kg/m2.
• Patients with previous procedures for the treatment of obesity.
• Pregnant females and lactating women.
• Patients with psychological or psychiatric disease
• Administration of antiemetic medication or systemic corticosteroids within 24 hours before surgery
• Patients who experienced vomiting within 24 hours before surgery.
• Patients with history of alcohol or drug abuse.
• Patients with hypersensitivity or contraindications to any of the drugs used in this study.