A nation-wide survey was conducted to estimate the prevalence of otitis media and allied diseases through physical examination by otolaryngologic doctors from July to October, 1991. A sample study population was selected from a panel to be representative of the Korean population by multistage clustered and stratified random sampling method based on the National Census Data, 1990. Total number of subjects undertaken were 9,321, Which were drawn from 2,899 households residing in 60 different areas throughout the country. The overall prevalence of otitis media was 2.85% (3.10% of males and 2.61% of females). Prevalence of each subtype was as follows; acute otitis media, 0.02%; middle ear effusion, 0.60%; chronic otitis media, 2.19%, respectively. The prevalence of otitis media did not vary by sex, nor by urban-rural difference. There was an increasing tendency of the prevalence of otitis media by age. However, the prevalence of both middle ear effusion and acute otitis media showed a decreasing pattern by age. Particularly noteworthy was a significant geographic variation in the prevalence of otitis media by provinces. The prevalence rate of septal deviation was 21.93% and the presence of septal deviation was significantly related to that of otitis media (p < 0.05). The prevalence rates of nasal allergic symptoms, nasal polyposis and evident cleft palate were 1.14%, 1.00% and 0.07%, respectively. The presence of otitis media was significantly correlated with both nasal allergic symptoms (P < 0.1) and evident cleft palate (P < 0.05), but not with that of nasal polyposis.