HIV infection induces both humoral and cytotoxic immune response. HIV is extremely efficient in evading host immune response due to virus adaptability. An immune response early in the course of HIV infection is probably the most important factor determining the outcome of the infection. A strong early immune response against efficient HIV antigens enables long-term prevention of aids development. A weak early cytotoxic immune response against HIV cannot control virus replication efficiently – a result may be early progression of infection towards aids. From that point of view the developement of vaccines against aids should induce a strong immune response against efficient HIV antigens. In that case a later HIV infection would be well controlled by the immune system thereby preventing a progression of infection towards aids.