Allergic fungal rhinosinusitis (AFRS) differs from other forms of polypous rhinosinusitis in its aggressive course and is often accompanied by bone destruction of the walls of the paranasal sinuses (SNP). In such cases, it is advisable to use an extended approach in endoscopic surgery. The article presents a clinical case of a 34-year-old patient with right-sided AFRS, accompanied by bone destruction of the anterior and posterior walls of the right frontal sinus, the medial wall of the orbit, and the development of right-sided proptosis. Previously, the patient underwent a radical maxillary sinusectomy on the right and two sparing endoscopic interventions on the SNP on the right, which were unsuccessful. The patient underwent endoscopic extended bilateral polysinusotomy, mega-anthrostomy on the right, extended endoscopic frontotomy of Draf III and resection of the middle concha on the right with complete removal of polyps and fungal mucin from the sinuses, as well as preservation of the mucous membrane of the surrounding structures. Surgical treatment was not accompanied by significant perioperative complications and led to the achievement of a complete and stable remission of the disease, improving the quality of life of the patient. Thus, extended endoscopic surgery of the paranasal sinuses, including mega-antrostomy and Draf III frontomy with preservation of the SNP mucosa, is an effective method for the treatment of aggressive forms of polyposis rhinosinusitis, especially AFRS.