Objective To determine the median effective dose (ED₅₀) of remidazolam for inducing loss of consciousness during general anesthesia induction in frail elderly patients undergoing elective non-cardiac surgery. Methods A total of 23 frail elderly patients who underwent elective non-cardiac surgery with general anesthesia in our hospital from April 2023 to August 2023 were enrolled in this study. Sequential method was used to determine the median effective dose of remimazolam. After a first intravenous injection dose of 0.2 mg/kg was given, their consciousness status within two minutes after medication was recorded. After the disappearance of consciousness, sulfentanil and rocuronium were administered before placement of a laryngeal mask. Regression equations were established with Probit regression. The 50% effective dose (ED₅₀), 95% effective dose (ED₉₅), and corresponding 95%CI were measured for the patients, and a dose-effect relationship diagram was plotted. The hemodynamic indicators at one (T2) and three minutes after anesthesia (T3), as well as the time of laryngeal mask placement (T4) were noted and compared with these indicators before anesthesia induction (T1). The occurrence of adverse reactions were recorded as well. SPSS statistics 26.0 was used for statistical analysis. Repeated measures ANOVA was performed to compare the data within the group.Results Remimazolam′s ED₅₀ of causing loss of consciousness in frail elderly patients was 0.091 mg/kg (95%CI 0.057-0.118 mg/kg), and its ED₉₅ was 0.142 mg/kg (95%CI 0.116-0.352 mg/kg). The mean arterial pressure at T2, T3 and T4 was significantly lower than that at T1 (P<0.05), but the decline was 20% lower than the baseline. There were no statistical differences in heart rates and pulse oxygen saturation at all above points. Hiccup was observed in two patients within two minutes after remimazolam injection, and both of them were transient. Conclusion For frail elderly patients, the ED₅₀ of remimazolam is 0.091 mg/kg in inducing loss of consciousness during general anesthesia induction, with stable hemodynamic parameters and low incidence of adverse reactions.