We report here the clinical evaluation of Amplicor polymerase chain reaction (PCR) assay for the detection of the human immunodeficiency virus type 1 (HIV-1) in peripheral blood mononuclear cells (PBMCs). Results obtained with Amplicor HIV-1 test were compared to serological status and a standard PCR assay using SK38/SK39 and oligomer hybridization with SK19. A panel of 208 well-characterized specimens was analyzed, including PBMC lysates from 47 antibody-negative high-risk individuals, eight antibody-negative low-risk subjects, two subjects with acute retroviral disease, 35 asymptomatic seropositive subjects (59 samples) with CD4 counts > 400/mm3, 31 patients (46 samples) with AIDS-related complex (ARC), 30 patients (40 specimens) with AIDS, and six seropositive patients with unknown clinical status. Amplicor demonstrated a specificity of 100% and a sensitivity of 98.7%. Of the two false-negative samples with Amplicor, one was negative for beta-globin amplification, whereas a dilution of the other sample turned positive for HIV-1. Inhibitors of Taq polymerase were thus believed to be responsible for the negative results. This study demonstrates that commercialized nonisotopic PCR assays reach adequate levels of sensitivity and specificity for diagnosis of HIV-1 infection and could be considered in clinical situations in which serology is not helpful.