OBJECTIVE: To analyze complications of endoscopic transsphenoidal surgery (ETS) for nonfunctioning pituitary macroadenomas (NFPAs).ăMETHODS: A retrospective study of 300 NFPAs was performed. Complications and factors that could influence these complications were analyzed.ăRESULTS: Visual and pituitary functions worsened in 2.4% and 13.7% of cases, respectively. Postoperative diabetes insipidus was permanent in 6.2% of cases. Postoperative meningitis occurred in 3.3% of patients. Meningitis was strongly associated with intraoperative cerebrospinal fluid (CSF) leaks (P = 0.01), postoperative CSF leaks (P = 0.0001), and operation times longer than 1 hour (P = 0.023). Detection of Staphylococcus aureus and preoperative treatment with mupirocin in the nostrils did not impact the occurrence of meningitis. Two patients with meningitis died (unique causes of death). Postoperative CSF leaks occurred in 2.7% of cases and were associated with intraoperative CSF leaks (P = 0.007) and permanent diabetes insipidus (P = 0.028). The rate of CSF leak decreased from 4% to 0.8% (P = 0.048) after we moved from a soft to hard reconstruction of the sella. The rate of postoperative epistaxis decreased from 6.7% to 1.25% after we stopped using monopolar coagulation (P = 0.013).ăCONCLUSIONS: ETS permits a wide view, allowing good conditions for a satisfactory resection in the majority of NFPAs. Some pitfalls of endoscopy can lead to complications that improve with modification of the operative technique (i.e., CSF leak and postoperative epistaxis). This study confirms an acceptable rate of complications associated with ETS.