HIV/AIDS is currently the leading cause of infectious disease mortality around the world. Since many alleles and/or haplotypes of HLA have been reported to be associated with progressive HIV infection, more detailed information on the HLA profile in HIV-1 infected individuals in Chongqing, southwest China would facilitate further understanding of HIV-1 infection, help AIDS vaccine design and the planning of effective preventive strategies. In this study, we performed 4-digit resolution HLA-A, B, DRB1 genotyping of 759 HIV-1 seropositive individuals using PCR-SSO methods. Six alleles were found at more than 10% high frequency: A*1101, A*0201, A*2402, B*4601, B*4001 and DRB1*0901. The most common 2- and 3-locus haplotypes were A*0201-B*4601, A*1101-B*4001, A*1101-B*4601, A*3303/1-B*5801, A*0201-B*4601-DRB1*0901, A*1101-B*4601-DRB1*0901 and A*3303/1-B*5801-DRB1*0301. 690 HIV-1 seropositive individuals with records of CD4 counts were divided into two groups: an AIDS patient group comprising 216 subjects with AIDS-defining symptoms and CD4 counts below 200 cells/mm(3) and an asymptomatic, HIV seropositive group of 474 subjects with a stable CD4 count of no less than 200 individuals. In the AIDS patient group, A*3303/1 and B*5801 alleles and the A*3303/1-B*5801 haplotype were significantly underrepresented as compared to the HIV-infected group, whereas A*1101-B*4001, A*1101-B*1502, A*2402-B*4801 haplotypes and five common haplotypes from two groups were significantly overrepresented. HLA-A or B and HLA-Bw6-Bw6 homozygotes were also overrepresented in the AIDS patients group. Our observations suggest that the presence of the B*3501 allele, A*2402-B*4801, common 2-locus and 3-locus haplotypes, HLA-A or B and Bw6-Bw6 homozygosity may predict a poor disease outcome in HIV-1 infection. However, HIV-1 infected individuals who have B*5801 alleles, A*3303/1-B*5801 haplotype and are heterozygous for Bw4-Bw6 are more likely to be resistant to progression of AIDS in this Chinese population.