Abstract We demonstrated recently that selective side-chain modification of functional cysteine-rich (Tat 21–40) and arginine-rich (Tat 53–68) domains of the HIV-1 Tat protein blocks pathogenic activities of these peptides while retaining their immunological characteristics. In the present study, we have synthesized a multiple-peptide conjugate system comprising modified Tat 21–40 and Tat 53–68 peptides (HIV-1-Tat-MPC). Immunization of mice with this highly homogeneous 10.7 kDa HIV-1-Tat-MPC synthetic construct induced an effective immune response in mice. The antibodies generated against HIV-1-Tat-MPC efficiently suppressed Tat-induced viral replication and significantly reduced HIV-associated cytopathic effects in human monocytes. These results indicate that epitope-specific antibodies directed against functional sites of Tat protein using non-pathogenic peptides inhibit HIV pathogenesis. The HIV-1-Tat-MPC, therefore, has potential for the development of a safe, effective, and economical therapeutic vaccine to reduce the progression of HIV infection.