Among the several risks encountered in endoscopic sinus surgery, catastrophic orbital bleeding and iatrogenic cerebrospinal fluid leak are the two serious complications surgeons most fear. This article discusses these avoidable complications and provides treatment algorithms for intraoperative maneuvers. A thorough understanding of the anatomy of the paranasal sinuses and their relationships with the anterior skull base, appropriate preoperative planning, and meticulous surgical technique are essential for preventing intraoperative cerebrospinal fluid leaks. Intraoperative orbital hematoma is discussed and a stepwise approach to reduce complications is provided.