BACKGROUND Obesity is a major global health issue associated with significant co-morbidities. Regarding its treatment, the use of bariatric procedures is increasing due to their efficacy in weight reduction and improved management of the associated medical conditions. Although comprehensive preoperative evaluation is essential, routine upper endoscopy is controversial. CASE REPORT We present the case of a 27-year-old woman with a history of morbid obesity, hypertension, and diabetes mellitus. She had multiple unsuccessful attempts at lifestyle modification for weight reduction. Accordingly, she was scheduled for sleeve gastrectomy. However, the operation was canceled due to the incidental intra-operative finding of a gastric mass. She was diagnosed as having gastric schwannoma, which is considered a rare gastrointestinal neoplasm. CONCLUSIONS Comprehensive preoperative evaluation of patients undergoing bariatric procedures is essential. The present case is a good example of the value of upper endoscopy in the evaluation of patients, including those who are asymptomatic.