Myringotomy was done on 44 three to four-year-old children out of a total of 463 three-year-olds in a geographically defined area, because these 44 children persistently showed abnormal screening-tympanometry over 6 months. The findings were correlated to middle ear pressure, absolute compliance, absolute gradient and relative gradient parameters. As regards the state of effusion in the middle ear, all parameters showed a high predictive value. A reverse proportionality of compliance parameters and the content of fluid in the tympanic cavity, each related to the magnitude of associated hearing loss, was demonstrated. The significance of the findings in the tympanometric diagnosis of middle ear disease in young children is outlined, and a revised classification system of the tympanogram, predicting middle ear effusion with a sensitivity of 91% and a specificity of 84%, is recommended.