Objective To analyze the efficacy of endoscopic surgery for frontal sinus meningoencephalocele and cerebrospinal fluid(CSF)leaks,and to explore endoscopic surgical strategy.Methods A total of 35 patients with frontal sinus meningoencephalocele and CSF leaks who underwent endoscopic transnasal surgery at Beijing Tongren Hospital,Capital Medical University between May 2007 and December 2023 were enrolled in this retrospective case series,including 29 males and 6 females,with the age of(35.23±15.76)years.High-resolution sinus CT and magnetic resonance cisternography were undertaken before surgery.The primary outcome measure was the success rate of endoscopic surgical repair.Statistical analysis was conducted using SPSS 27 and GraphPad Prism 8 software.Results Of the 35 cases,21(60.0%)were traumatic,and 14(40.0%)were non-traumatic.The most common defect was in the posterior frontal sinus wall(24 cases,68.6%),with a defect size of(10.4±4.8)mm2.Twenty-six cases(74.3%)underwent endoscopic transnasal Draf Ⅱ a-Ⅲ frontal sinusotomy,and 9 cases(25.7%)underwent endoscopic transnasal Darf Ⅱ b-Ⅲ frontal sinusotomy combined with frontal trephination.The average follow-up time was(84.72±57.42)months.The success rate of one-time endoscopic repair was 97.1%(34/35).One patient required a second procedure,resulting in an overall success rate of 100%.Thirty-three patients had a widely patent frontal sinus ostium postoperatively,while two experienced stenosis.Conclusions Endoscopic surgery is effective for treating frontal meningoencephalocele and CSF leaks while preserving frontal sinus drainage.Combined frontal trephination is recommended for defects that are difficult to repair using the conventional transnasal approach.