Nasal obstruction is a common pediatric clinical complaint that involves a great number of pathologies (allergic rhinopaty, adenoid hypertrophy, septal deformities, infeccious sinusitis, tumours, choanal atresia, nasal foreign bodies, etc.). Not only the history, and a through physical examination but also, the subsidiary exams are of great value in the etiologic diagnostic. Antro-choanal polyp (Killian's polyp) must be remembered in the differential diagnosis of nasal obstruction, when a sinus roentgenogram with unilateral maxillary opacification is seen. Clinically, the lesion often protudes into the nasopharynx and in some cases it may even be seen extending into the oropharynx. The surgical procedure usually employed is a unilateral Caldwell- Luc antrostomy, with oropharyngeal remotion. We present 12 pediatric patients with antral-choanal polyps, and discuss history, radiology, nasal/nasopharyngeal endoscopic evaluation, considerations about the origin and surgical treatment of choice.