We investigated the relationships between class II human leukocyte antigens (HLA) and the antibody response to Plasmodium falciparum p126 protein and to its amino-terminal portion (Nt47) in 2 malaria-endemic villages in Brazil, Colina and Ribeirinha. All people from the endemic areas had anti-p126 antibodies, and the frequencies of anti-Nt47 antibodies were similar in both communities (66% for Colina and 75% for Ribeirinha). Typing of HLA showed that Colina and Ribeirinha groups had no significant differences in HLA antigen frequencies. However, in both groups, significant associations between positive response to anti-Nt47 and presence of HLA-DR4, as well as between absence of response and presence of HLA-DR15, were observed. The predominance of positive responses to Nt47 among HLA-DR4 people was independent of the presence of any particular allele. There was no evidence for association between HLA-DQB1 alleles and antibody response to Nt47. Thus, naturally exposed people with different HLA class II antigens seem to respond differently to Nt47, indicating that the choice of relevant peptide sequences may have important consequences for subunit vaccine development.