An anti-HIV-1/HIV-2 line immunoassay (LIA), using peptides and recombinant antigens was evaluated against commercially available Western blot tests for HIV-1 and HIV-2 antibodies. Two thousand one hundred and ten sera of European, African, and South American origin were used in the evaluation. The panel included 1066 sera with antibodies to HIV-1, 192 sera with antibodies to HIV-2, and 64 sera with antibodies to both. Using Western blot results interpreted according to the WHO criteria as a reference standard, the overall specificity obtained by this LIA was 100 % and the sensitivity was 99.77 % (97.51-100 % for 95 % confidence limits) when sera dually reactive in Western blot were included. Of the three sera negative in the LIA but positive in HIV-1 WB, two could be retested in a radioimmunoprecipitation assay and were negative. When dually reactive sera in the Western blot (WHO) were included, the LIA yielded 9.9 % indeterminate results as compared with 15.5 % for both assays (x ²=29.30; p<0.001). although="" only="" one="" hiv-2="" specific="" peptide="" antigen="" (gp36)="" was="" used,="" the="" lia="" yielded="" a="" specificity="" of="" 100="" %="" and="" a="" sensitivity="" of="" 100="" %="" as="" compared="" with="" the="" hiv-2="" western="" blot="" assay.="" when="" indeterminate="" results="" were="" included,="" the="" overall="" agreement="" between="" the="" lia="" and="" the="" hiv-1="" and="" hiv-2="" western="" blot="" (who="" criteria)="" was="" 89.9="" %="" and="" 90.1="" %="" respectively.="" these="" results="" indicate="" that="" the="" lia="" provides="" reliable="" simultaneous="" detection="" of="" antibodies="" to="" hiv-1="" and="" hiv-2,="" and="" at="" a="" cost="" which="" is="" substantially="" lower="" than="" the="" cost="" of="" western="" blot="">