Some neutralizing epitopes on HIV-1 envelope proteins were shown to induce antibodies that could effectively inhibit the infection of different HIV-1 strains in vitro) But only very low levels of antibodies to these epitopes were determined in the HIV-1 infected individuals) In this study, the aluminum(alum)adjuvant to increase the immunogenicity of the neutralizing epitopes was used) Three epitope-peptides wC-(ELDKWAG)4, C-(RILAVERYLKD-G)2and C-(GPGRAFY)2 x, which contain three epitopes(ELDKWA, RILAVERYLKD, GPGRAFY)from the HIV-1 Env proteins, were synthesized and conjugated to carrier protein keyhole limpet hemocyanin(KLH)) The epitope-vaccines C-(ELDKWAG)4-KLH and C(RILAVERYLKD-G)2-KLH in alum induced high levels of epitope-specific antibodies recognizing the epitopes from epitope-peptides C-(ELDKWAG)4and C-(RILAVERYLKD-G)2, as well as the gp41 C-domain peptides P2 wCTSLIHSLIEESQNQQEKNEQELLELDKWA(aa 646-674)xand P1wLQARILAVERYLKDQQL(aa 583-599)x and the recombinant soluble gp41(rsgp41)bearing both epitopes(antibody titer in rabbit sera was 1:12800-25,600 dilution)) Immunoblotting analysis demonstrated that the antibodies in both antisera bound to rsgp41, indicating that both antibodies recognized the natural epitopes on rsgp41 protein) The epitope-vaccines C-(GPGRAFY)2-KLH induced moderate GPGRAFY epitope-specific antibody response with a titer of 1:6400) In contrast, as it was demonstrated in previous studies, the immunization with rgp160 induced weak antibody response to these three epitopes(titer of 1:400-1600)) This suggests that E pitope-peptides conjugated to KLH when infected with alum significantly increases immunogenicity of gp41 neutralizing epitopes providing a hope for the development of an HIV-1 vaccine)