This study compared he Single-Use Diagnostic HIV-1 antibody screening a test (SUDS; Murex, Norcross, Ga) with the HIVAB HIV-1 EIA screen (Abbott Diagnostics, Abbott Park, Ill). The SUDS test was challenged with 251 random patient samples 86 samples from patients With various non-HIV immunologic-related conditions, and 38 samples from patients with confirmed HIV infections. All 38 of the Western blot-confirmed HIV samples were detected as positive by the SUDS test. Of the randomly selected patient samples 244 of 251 were negative by the Murex procedure. The seven positive results were individually investigated and found to have been from patients with previous diagnosis of HIV infection. Seventy-eight of the 86 specimens from patients with non-HIV conditions tested negative by both methods. Western blot results on the 8 discrepant HIV-1 antibody-positive samples were negative or indeterminate. Five SUDS false-positive results were found in two patients with monoclonal gammopathies, one patient with a high-titer mitochondrial antibody, one patient with active mycoplasma infection, and one patient with a markedly elevated prostate-specific antigen. When confirmed by Western blot, the SUDS test was 100% sensitive and 98.4% specific.