We retrospectively reviewed the cases of 27 patients who experienced intraoperative bleeding during resection of a large (Fisch type III or IV) juvenile nasopharyngeal angiofibroma (JNA). Of this group, 16 patients had a type III JNA and 11 had a type IV tumor. The degree of hemorrhaging during excision of these JNAs varied greatly among individual patients. The amount of blood lost ranged from 200 to 5,000 ml (mean: 1,800) in the type III cases and from 700 to 8,000 ml (mean: 2,850) in the type IV cases. In 5 of these cases, both intraoperative observations and imaging data suggested that an important factor in the blood loss was damage to the pterygoid venous plexus (PVP). The PVP communicates with the cavernous sinus, ophthalmic vein, maxillary vein, and facial vein; no valve exists between these veins. In patients with a large JNA, the PVP is usually compressed by or adherent to the tumor. When a PVP is seriously damaged during removal of a JNA, hemorrhaging can be very profuse. Therefore, a suitable surgical approach and appropriate hemostatic procedures should be used to prevent or manage PVP hemorrhage as effectively as possible. We also describe in greater detail 5 typical cases of JNA excision that did (n = 3) and did not (n = 2) involve PVP damage.