ObjectivesTo determine the safety and efficacy of deep neuromuscular block (NMB) for endolaryngeal surgery. Data SourcesPubMed, Web of Science, Cochrane Library, Ovid Medline, Embase, China National Knowledge Infrastructure, Wanfang, VIP databases, and trial registry database. MethodsInclusion criteria followed the PICOS principles: Participants, adults undergoing endolaryngeal surgery; Intervention, deep NMB performed during the surgery; Control, no-deep NMB performed; Outcomes, primary outcome: the incidence of clinically acceptable surgical conditions. Secondary outcome: the incidence of intraoperative complications (including vocal fold movement and coughing) and total incidence of postoperative complications [including postoperative residual curarization (PORC), postoperative sore throat (POST), and postoperative nausea and vomiting (PONV)]. Study design, randomized controlled trials (RCTs). Duplicate publications, editorials, letters, abstracts, and reviews were excluded. ResultsFour articles with 242 patients were identified for analysis. The results indicated that compared with no-deep NMB, deep NMB provides a higher incidence of clinically acceptable surgical conditions (98.36% vs. 76.67%; relative ratio [RR] = 1.29, 95% CI: 1.07-1.56), a lower incidence of intraoperative complications (10.83% versus 37.16%; RR = 0.32; 95% CI: 0.21-0.49) (lower incidence of vocal fold movement [1.85% vs. 34%; RR = 0.08, 95% CI: 0.02-0.41] and coughing [15.53% vs. 38.78%; RR = 0.42, 95% CI: 0.27-0.66]). There were no differences in the overall incidence of postoperative complications (RR = 2.10, 95% CI: 0.12-36.40). ConclusionsBased on current published evidence, deep NMB provides better surgical conditions with a higher incidence of clinically acceptable surgical conditions and a lower incidence of intraoperative complications (lower incidence of vocal fold movement and coughing) without increasing the overall incidence of postoperative complications. Level of EvidenceI Laryngoscope, 2023