Background: Remimazolam besylate is a new type of benzodiazepine that has the characteristics of quick effects, short maintenance and recovery times, and no accumulation. Compound opioids can have a sedative effect in some endoscopic examinations. This trial was conducted to confirm the efficacy and safety of remimazolam besylate versus propofol during hysteroscopy.Methods: Patients undergoing hysteroscopy were randomly assigned to either the remimazolam (Group R, n=41) or the propofol group (Group P, n=41). Group R was administered an induction dosage of 0.2 mg/kg/min and a maintenance dosage of 1 mg/kg/h. Group P was started at 1.5-2.0 mg/kg propofol for up to 60-100 s and then maintained at 3.0-6.0 mg/kg/h. In both groups, remifentanil was infused using a target-controlled infusion system with a target concentration of 1.5 ng/ml and titrated during the procedure. The incidence rates of body movement and various adverse events in both groups were compared.Results: Eighty-two patients were included in this study. The incidence of adverse events in Group R (8.5%) was significantly lower than that in Group P (36.6%) (P < 0.05). Injection pain, postoperative dizziness and low SpO2 were the most common adverse events (P < 0.05). Compared with Group P patients, Group R patients recovered faster, had a shorter residence time in the PACU, and exhibited a higher quality of recovery (P < 0.05).Conclusion: Remimazolam besylate can provide safe and effective sedation for hysteroscopy. The depth of sedation is sufficient and effective, and the quality of recovery is high. Moreover, adverse events such as haemodynamic fluctuation, excessive sedation depth, low SpO2 and injection pain caused by propofol are largely avoided.Trial registrationThis study was approved by the Clinical Research Ethics Committee of Mengcheng County No.1 People's Hospital (2020MYL20003) and registered at http:// www.chictr.org.cn (15/09/2020, ChiCTR-2000038252). The study protocol is performed in the relevant guidelines.