Antrochoanal polyps arise from the maxillary sinuses and are the much less common. Ojective : The description a lesion on the CT scan and compare with the clinical, histopathplogical of the Antrochoanal polyps. Materials and Methods: Case study of 40 patients Antrochoanal polyps, operateds at Hospital ENT Central (2007-2009). Diagnostic clinical, endoscopic, CT scan, histopathologies of HE and PAS. Results ,and discussions: The average age 32-43 years (17.5 percent 15 years). The opaque on one side from the sinus to medial meatus is specifical of polyp Killian on CT. There is not a destruction of bone. The definition of the origin of polyp is 100 percent on the operations and the only 20 percent on the CT. The malformation of nasal and meatus is 75 percent, and are etiological of the polyp Killian (p 0.01): Conclusion: The CT and endoscopic are the goldal standards of the diagnostic of the polyp Killian.