A follow-up study of 1177 adult patients who had had atopic dermatitis (AD) (Groups 1 and 2) or respiratory allergy (Group 3) in childhood is reported. Patients who had had AD in childhood had received in-patient (Group 1) or out-patient treatment (Group 2) for their dermatitis. 183 patients in Group 1 and 162 in Group 2 were examined clinically. Further, 445 patients who had recently been treated for hand eczema at a department for occupational dermatoses were studied (Group 5). A group of 199 people who had no personal or family history of atopy served as controls (Group 4). The essential findings were as follows: The healing rate was lower (38%) in patients with severe (Group 1) than in those with moderate (60%) childhood dermatitis (Group 2). Although the healing rate was comparatively low in both groups, persistent eczema was in most cases of mild degree. The commonest localization of persistent dermatitis was the hands. The AD had developed earlier in patients who had had severe childhood dermatitis than in those whose childhood AD was moderate. Severe childhood AD was also associated with a significantly higher frequency of family history of atopy and associated respiratory allergy. The inheritance pattern was specific for the different types of atopic disease. A family history of AD was significantly commoner in people with AD than in people with respiratory allergy, and, conversely, people with a family history of respiratory allergy had developed asthma or allergic rhinitis rather than AD. The serum IgE level was raised in 45% and 26% of the clinically examined individuals in Groups 1 and 2, respectively. A comparatively large proportion of patients with persistent or recurrent dermatitis had normal IgE values. There was a strong correlation between the extent of persistent dermatitis and serum IgE levels. It is concluded that the serum IgE cannot be used to establish the diagnosis of atopic dermatitis. The number of contact sensitized people was greater in Group 2 (23%) than in Group 1 (17%). Occurrence of contact sensitivity, which was demonstrable in a total of 20% of the patch tested individuals from Groups 1 and 2, was not correlated to prevalence of healing at the time of examination. Fragrance-mix and balsam of Peru were the commonest contact sensitizers. People with a history of AD showed a higher incidence of recurrent (greater than 5 episodes per year) cold sores, upper respiratory infection, and herpes zoster than non-atopic controls.(ABSTRACT TRUNCATED AT 400 WORDS)