The operative findings in a homogeneous, preoperatively followed population of 46 3- to 4-year-old children with middle ear effusion treated by adenotomy and paracentesis were correlated with the results of pre- and postoperative tympanometry. Factors of prognostic value were only the immediate type of tympanogram and the quantity of the middle ear effusion, not its viscosity. The combination of the determinative factors divided the material into four groups showing a different course through a 6-month postoperative follow-up. A flat tympanogram and impacted fluid spelt the poorest prognosis, with about 60% recurrences. The influence of the results upon a differentiated treatment of secretory otitis media in the younger age groups is outlined.