Abstract Objective The study aimed to analyze complications of endoscopic transsphenoidal surgery (ETS) for nonfunctioning pituitary adenomas (NFPAs). Methods A retrospective study of 300 NFPAs was carried out. Complications and factors that could influence these complications were analyzed. Results 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. It was strongly associated with intraoperative cerebrospinal fluid (CSF) leaks ( p = 0.01), postoperative CSF leaks ( p = 0.0001), and operation times of more 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 cause 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 fell from 4% to 0.8% ( p = 0.01) after we moved from a soft to hard reconstruction of the sella. The rate of postoperative epistaxis fell from 6.7% to 1.25% after we stopped using the monopolar coagulation ( p = 0.013). Conclusions 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.