Objective: The use of sedation in upper gastrointestinal endoscopy is widespread because of better patient tolerance. As this sedation is usually performed by non-anesthesiologists in and outside of hospital settings, possible adverse effects arising during the procedure must be dealt with carefully. In this study, the safety and efficacy of midazolam for conscious sedation in 100 patients undergoing upper gastrointestinal endoscopy were evaluated prospectively. Patients and Methods: Hundred consecutive patients undergoing upper gastrointestinal endoscopy were sedated with intravenous midazolam. The dose of midazolam was titrated according to the patient's need and the duration of the procedure. Heart rate and oxygen saturation of all the patients were continuously monitored during the procedure and any complications were recorded. The amnesic effect of midazolam and patient comfort were also evaluated. Results: During the procedure, absence of oxygen desaturation (SaO₂&