The aim of this study is to evaluate the long-term results of endoscopic sinus surgery in the treatment of antrochoanal polyps and the role of extending the middle meatal antrostomy on the expense of the inferior meatus in providing wide exposure and accessibility within the maxillary sinus to ensure complete removal of its antral portion. Thirty-six patients were reviewed. Two groups were identified: Group A including patients with antrochoanal polyps that were resected endoscopically through a classical wide middle meatal antrostomy and Group B which included those who underwent endoscopic removal via an extension of the antrostomy inferiorly through submucosal resection of the lateral bony skeleton of the inferior meatus. There were 13 female and 23 male patients with a mean age of 28 ± 9.4 years. The mean follow-up period was 20.4 ± 6.7 months. Six patients were recurrent after previous endoscopic surgery. Group A included 17 patients and the remaining 19 patients were assigned to Group B. Two patients from Group A developed symptomatic recurrence and were cured with revision extended antrostomy. Three patients showed endoscopic evidence of a developing cystic lesion within the maxillary sinus that was punctured through the wide antrostomy. Endoscopic resection is considered the main treatment modality of antrochoanal polyps. Modification of the technique through removal of the lateral bony skeleton of the inferior meatus with downward displacement of the inferior turbinate provided accessibility to the inferior and prelacrimal recesses of the maxillary sinus.