Data on respiratory conditions reported by sample persons 12 to 74 years of age in NHANES II were examined. The prevalence of upper respiratory conditions varied little between whites (N = 11,260) and blacks (N = 1,482): allergic rhinitis 9.8% versus 8.1%; chronic rhinitis 20.4% versus 19.2%. Except for "allergic rhinitis only," which was increased in whites, no racial differences were found for any upper respiratory condition, singly or in combination. The prevalence of lower respiratory conditions in whites and blacks were: asthma (A) 6.9% versus 9.2% P less than .05, chronic bronchitis (CB) 1.3% versus 0.8% P less than .05, and chronic cough (CC) 1.1% versus 0.7% P greater than .05. There was no racial difference in the prevalence of overall lower respiratory conditions (A + CC + CB). All upper and lower respiratory conditions peaked in 50 to 74-year-olds except for allergic rhinitis only (without asthma) which peaked in 25 to 49-year-olds. Smokers reported all upper and lower respiratory conditions more often than nonsmokers, except for allergic rhinitis only (without asthma), which was reported less often by smokers. Females reported more allergic rhinitis in any combination, while males reported more asthma only (without allergic rhinitis). Sample persons living below poverty reported increased prevalence of chronic rhinitis, asthma, asthma only (without allergic rhinitis), and either allergic rhinitis or asthma. Residents of urban areas reported increased prevalence of allergic rhinitis and allergic rhinitis only (without asthma) while residents of rural areas reported increased prevalence of asthma only (without allergic rhinitis).(ABSTRACT TRUNCATED AT 250 WORDS)