The prevelance of chronic secretory otitis media was studied in 5414 children aged 2-12 yr. The maximum incidence of the disease was at the age of 2 yr decreasing progressively to the age of 12, the results fitting a logarithmic curve. Of all the children, 8.7% had chronic otitis media, 0.59% had adhesive otitis and 0.35% chronic suppurative otitis media. The prevalence of secretory otitis was, significantly, related to infections of the upper respiratory tract and to nasal obstruction. The part played by the adenoid was more questionable. Purulent otorrhoea was more frequent in those children with secretory otitis than normal children.