BackgroundDexmedetomidine (DEX) is a novel, highly selective α2-adrenoceptor agonist that elicits sedative, amnestic, sympatholytic and analgesic effects in patients. Several Japanese investigators have reported the clinical usefulness of DEX for sedation in endoscopic therapies for gastrointestinal malignancies; however, there have been limited data regarding the usefulness and safety of DEX for sedation during endoscopic procedures for oesophageal varices (OVs), such as endoscopic injection sclerotherapy (EIS). In this prospective, single-arm interventional study, we aimed to elucidate these issues.MethodsPatients who require two or more sessions of prophylactic EIS for the treatment of OVs will be enrolled in this prospective interventional study. EIS procedures include two methods: (1) sedation during endoscopic procedures will be performed using conventional methods (pentazocine (PNZ) and midazolam (MDZ)), and (2) sedation during endoscopic procedures will be performed using PNZ, low-dose MDZ and DEX. These two methods were randomly assigned in the first and second EIS. The effect and safety of these two procedures with respect to patient sedation are to be compared with the degree of sedation evaluated using the Bispectral Index monitoring system (Aspect Medical Systems, Norwood, Massachusetts, USA).Ethics and disseminationThis study received approval from the Institutional Review Board at Hyogo College of Medicine (approval no. 2324). The authors are committed to publishing the study results as widely as possible in peer-reviewed journals, and to ensuring that appropriate recognition is provided to everyone who is working on this study.Trial registration numberUMIN000026688; Pre-results.