Paracentesis was performed on 46 three- to four-year-old children out of all 523 three-year-olds in a geographically defined area, because these 46 children had persistently showed abnormal tympanograms over a 6-month period. The findings were correlated to the parameters middle ear pressure, absolute compliance, absolute gradient, and relative gradient. As regards the state of effusion in the middle ear, all these parameters--except for the middle ear pressure--showed a high predictive value. The significance of the findings in the tympanometric diagnosis of middle ear disease in the younger age groups is outlined.