ObjectiveTo analyze the therapeutic effect of transnasal endoscopic surgery for skull base chordomas. MethodsClinical data of 87 patients suffering from skull base chordomas surgically treated via endonasal endoscopic approach between Mar 2011 and Jan 2018 were analyzed retrospectively. The factors influencing the tumor resection rate and therapeutic effect were summarized and analyzed.ResultsIn general, gross total resection (GTR) was achieved in 37 cases (42.5%,37/87). Of them, the GTR rates were 40.0%(28/70), 63.6%(7/11), and 33.3%(2/6) in the patients with tumor located at the superior, middle and inferior third of the clivus, respectively. According to the Al Mefty classification system, the GTR rates via transnasal endoscopic approach were 75.0% (9/12), 40.0% (8/20) and 36.4% (20/55) in patients of type I, type II and type III, respectively. In recent years (from Dec 2014 to Jan 2018), GTR was achieved in 48.8% (21/43) of the patients, which appeared considerably higher than that in earlier time (from Mar 2011 to Dec 2014) (36.4%, 16/44). Most patients (86.2%) had no temporary postoperative complications. 27 (54%) of the 50 cases without GTR underwent carbon ion radiotherapy, and 88.9% of them had no recurrence. Statistical analysis revealed that the tumor resection rate was insignificantly correlated to patients’ gender and age, surgical or radiotherapy history, as well as size and location of tumor (all P>0.05).ConclusionTransnasal endoscopic surgery is an effective surgical method for the treatment of skull base chordomas even if the therapeutic effect is unsatisfactory for tumors located at the inferior third of the clivus, especially those with invasion of lateral skull base. The therapeutic effect of transnasal endoscopic surgery for skull base chordomas can be further improved with the accumulation of surgeons’ experience and postoperative application of carbon ion radiotherapy.