Repetitive tympanometric screenings of healthy 1-year-old and 2-year-old children showed that 36% of all healthy children had a type B tympanogram, indicating middle ear effusion or secretory otitis, at least once during the first 2 years of life. Another 29% of children had a middle ear pressure of -200 to -350 mm H2O. It was rendered probable that at least 75% of all healthy children have secretory otitis in the course of the first 8 years of life. This high frequency of secretory otitis is correlated to the histology of the normal middle ear mucosa. The many conflicting opinions that prevail in the literature concerning the compostion of the normal middle ear mucosa, especially concerning the demonstration of mucous glands, probably arise from the fact that the middle ear mucosa of most healthy adults has been exposed to metaplastic changes in childhood but has normalized except for minor sequelae. These are often misinterpreted as constituting components of the normal mucosa.