Natural-orifice transluminal endoscopic surgery (NOTES) is an emerging transluminal technique in which interventions are carried out by entering the abdominal cavity via a natural orifice such as the stomach. Infection is a potential risk of the procedure, and the potential pathogens are different from those encountered with skin incisions. Currently, available data regarding prophylactic anti-infective treatment are limited. We compared the effectiveness of topical antimicrobial lavage of mouth and stomach and proton pump inhibitor therapy with gastric cleansing with sterile saline solution in preventing NOTES-related contamination and infection.