Tympanometry was repeated 3, months after the first evaluation of 254 healthy 2-year-old children. Although the total distribution of tympanogram types was the same at the second as at the primary evaluation, 14% of the ears showing type B indicating middle ear effusion, and 38.6% having a negative middle ear pressure of – 100 mmH2O or less, the types altered in 51.8% of all ears. Type B had improved in 5 3% of the ears in which it was originally found, indicating a considerable tendency to spontaneous improvement of secretory otitis. Alterations in the tympanometric findings were due predominantly to a change in the frequency of catarrhalia.