Human herpesvirus 8 (HHV-8) antibody tests vary in sensitivity and specificity, depending on the population tested and on the type of assay. In this study, we evaluated the sensitivity and specificity of two peptide enzyme immunoassays using a multiple antigenic peptide (PK8.1-MAP) or a chimeric peptide (PK8.1-orf65) as the antigens and determined the HHV-8 seroprevalence in different Argentine populations using an immunofluorescence assay (IFA) as reference. For analysis, when either or both of the peptide EIAs were positive, the specimen was considered positive (PEIA). We estimated the sensitivity and specificity of PEIA to be 97% using Kaposi's sarcoma (KS) patients and healthy individuals as positive and negative controls respectively. Then, we expanded the control groups to include IFA positive men who have sex with men (MSM) and IFA negative blood donors. The sensitivity decreased to 83% but specificity remained high at 98%. Concordance between PEIA and IFA was 77% for 1/40 IFA titers and increased to 90% for titers >or=1/160. Seroprevalences for HHV-8 performed in the HIV positive MSM were (IFA 73.1%; PEIA55.2%); heterosexuals (52.5%, 22.2%), which includes injecting drug users (IDU) (54.0%, 32.4%) and non-IDU (51.6%, 16.1%). The inclusion of non-KS HHV-8 IFA positive individuals to the positive controls may be a substantial improvement towards the realistic assessment of assay sensitivity. These peptide EIAs can be used for trends in populations with high probability of being HHV-8 infected and negative results should be confirmed by IFA. IFA test is still the most suitable test for populations with low probabilities of being infected.