This study examined the epidemiological aspects of asthma and wheezy bronchitis at 16 years of age in children of a large British National cohort previously studied at the time of birth and when they were 7 and 11. It confirmed, for age 16, the steady decline in numbers of children suffering from asthma or wheezy bronchitis previously seen between ages 7 and 11. Significantly more boys than girls continued to report having these ailments. At age 16, children with asthma were more likely than those without to suffer from such allergy-related conditions as eczema and to come from homes where the principal wage-earner has a nonmanual job and where both mother and child smoke.