HIV infection is associated with immune dysregulation primarily affecting T-cell function, whereas asthma is related to excessive T-cell activity. We compared the prevalence of asthma and related conditions among adult seropositive men with the prevalence among men of similar age drawn from the general population. Seropositive men had a significantly more frequent occurrence of wheezing (54.4 versus 21.2%), bronchial hyperresponsiveness (BHR) to methacholine (26.2 versus 14.4%), and an elevated total serum IgE (37.8 versus 25.7%). Differences in BHR were significant only among smokers. Among the seropositive men, FEV(1)/FVC and an elevated IgE were the principal determinants of BHR. Our results suggest that the frequency of asthma may be underestimated in HIV disease. Furthermore, the frequent occurrence of BHR in HIV-infected men who smoke (30.1%) suggests this group may be especially susceptible to the adverse effects of cigarette smoke.