Human immunodeficiency virus type 1 (HIV-1) may enter the blood stream as free virus or via infected lymphocytes, which poses problems for vaccine development. The classical vaccine designs, attenuated, inactivated, or subunit vaccine will be discussed with regard to HIV. Development of a recombinant subunit vaccine appears to be the most promising approach. Forthcoming results from experiments involving inoculation of chimpanzees should allow evaluation of the feasibility of using a subunit vaccine based on the env-glycoprotein. Also the use of live recombinant vaccinia merits further investigation.