Epidemiological data on middle-ear pathology during pre-school age are lacking despite the striking frequency of middle-ear symptoms in this age group. To evaluate the applicability of the impedance test in the younger age groups and to make an epidemiological study of the distribution of tympanogram types in a normal group of preschool children, an attempt was made to examine all 523 3-year-olds in a limited geographic area. 1005 ears in 504 children (96.4% of those invited) were fully investigated with tympanometry and otoscopy with Siegle's speculum within 4 weeks. 62.8% of the ears showed type A tympanometric curves, 9.8% type B and 27.4% type C. Bilateral type A tympanometric curves were found in 276 children (55.4%). The prevalence of abnormal tympanometry proved to be unexpectedly high in both sexes. This finding is discussed. Even with the use of conventional technique and standard equipment, the 3-year-old clientele presented no testing problems.