Objective To determine the effect of using entropy index (EI) for monitoring anesthesia depth on the quality and anesthetic dose of laryngeal mask anesthesia in the elderly patients undergoing fiberoptic bronchoscopy. Methods Sixty-four elderly patients (29 males and 35 females, over 64 years old) who underwent elective fiberoptic bronchoscopy in our hospital were randomized into control (Group C) and EI monitoring group (Group EI), with 32 cases in each group. The drug used in Group C were adjusted according to the results of conventional anesthetic depth monitoring, while those of Group EI were under the guidance of EI. Propofol and remifentanil dual channel target controlled infusion was applied for the both groups. Heart rate (HR), mean arterial pressure (MAP) and oxygen saturation at each time point and the doses of propofol and remifentanil were detected. The time for checking, eye opening, extubation and awakening was also recorded. The adverse reactions such as nausea, vomitting and restless within 24 h postoperatively and intraoperative awareness were observed. Patient’s and bronchoscopy physicians’ satisfaction scores were evaluated. Results Compared with Group C, Group EI had less amounts of propofol and remifentanil, shorter time of eye opening, extubation and awakening, lower incidences of nausea and vomitting in 24 h after operation (P<0.05), and higher patient’s and physician’s satisfaction scores (P<0.05). Conclusion EI monitoring can improve the quality and save the cost of laryngeal mask anesthesia in the elderly patients undergoing fiberoptic bronchoscopy.