The objectives of this preliminary study were to determine the prevalence of oral candidal carriage and infection in a group of HIV-positive individuals and compare the humoral immune responses in serum and saliva in this group with a control group of HIV-negative subjects. Patients were examined clinically with particular reference to the presence of candidal lesions and oral swabs taken to identify carriers. Venous blood and whole saliva were obtained for estimation of total and anti-Candida antibody levels. Pseudomembranous candidiasis was the commonest clinical variant in HIV-positive individuals. Candida albicans was the commonest species isolated in both groups. Increased levels of anti-Candida IgG were found in both serum and saliva of HIV-negative individuals who were either carriers of Candida species or had clinical candidiasis. This was associated with a reciprocal fall in anti-Candida IgA. Similar trends were seen in HIV-positive individuals in association with candidal carriage and infection, although the changes were more marked.