We retrospectively investigated the efficacy and safety of propofol administration alone and in combination with midazolam for gag reflex suppression during dental treatment under intravenous sedation. We included 56 patients with an overactive gag reflex who were to undergo dental treatment under intravenous sedation. They were divided into propofol (P group, n = 22) and midazolam with propofol (MP group, n = 34) groups. The P group received propofol alone, while the MP group received midazolam (0.04 mg/kg) prior to target-controlled infusion (TCI) of propofol (titrated for adequate sedation). The patients' anesthetic records were evaluated for vital sign changes, adverse cardiovascular or respiratory event frequency, the number of forced treatment interruptions, and the TCI-predicted cerebral propofol concentration at gag reflex suppression (posterior tongue stimulation with a dental mirror). No significant differences were observed between the 2 groups preoperatively. There were no cases of forced interruptions or significant respiratory compromise in either group. Cardiovascular adverse event frequency was lower in the MP group than in the P group (all p < .05). Our results suggest that propofol, when combined with midazolam, minimized cardiovascular effects compared with propofol alone when used to suppress the gag reflex in patients during dental treatment under intravenous sedation.