One of the major ENT complaints is chronic nasal obstruction. A definite relation between nasal obstruction and middle ear diseases, where Eustachian tube dysfunction (ETD) caused by nasal obstruction, that may cause middle ear hypoventilation resulting in otitis media with effusion (OME), that may be definitely diagnosed through use of otoscopic findings associated with type B tympanogram. This paper aimed to compare the effect of sinonasal polyposis and non-polyposis nasal obstruction on middle ear and Eustachian tube (ET) functions. Case control study was conducted on 90 randomly selected patients, above15 years, divided into three groups Group (1): included 30 patients with nasal obstruction due to sinonasal polyposis. Group (2) included 30 patients with nasal obstruction due to nasal allergy. Group (3) (control): included healthy people free of nasal obstruction. Patients were subjected to detailed history taking proper clinical examination, Computed tomography scan of the nose and para nasal sinuses, Eustachian tube functions, audiometry and tympanometry. There was a statistically significant difference between groups according to complaints, Tympanogram, degree of hearing loss and Eustachian tube function, higher in group (1) than group (2) and control. The ET functions (Tympanometry, Swallowing step and Toynbee test) in the polyposis patients and allergic patients without polyposis seems to be disturbed. This is probably due to the inflammation and infection associated with polyposis and allergy.