Sažetak The aim of the study was to assess the relationship between the classification of Eustachian tube functions and the prognosis of the development of secretory otitis media. The study included 66 children (116 ears) aged 3 to 14 years with chronic otitis media with effusion. Tympanocentesis was performed after unsuccessful conservative treatment. During the period of wearing tympanostomy tubes, equalizing of air pressure at both ends of the Eustachian tube was assessed by tubotympanometry at 1, 3, 6 and 12 months. Study children were divided into four groups according to the ability of equalizing air pressure. Study results pointed to the following conclusions: equalization of air pressure was worse in children aged 3-8 was than in those aged 5-14; and the results of eustachian tube functions were best after 1-year period of wearing tympanostomy tubes.