The advent of recombinant DNA technology heralded a new chapter for the production of a wide range of therapeutic agents in sufficient quantities for human use. The commercial exploitation of recombinant DNA (rDNA) technology began in late 1970s by biotechnological companies to produce proteins. There are around 400 different proteins being produced by rDNA technology and as of now around 30 have been approved for human use. Recombinant DNA technology involves using microorganisms, macroscopic organisms, or hybrids of tumor cells and leukocytes: to create new pharmaceuticals; to create safer and/or more effective versions of conventionally produced pharmaceuticals; and to produce substances identical to conventionally made pharmaceuticals more cost-effectively than the latter pharmaceuticals are produced. Recombinant DNA technology enables modifying microorganisms, animals, and plants so that they yield medically useful substances, particularly scarce human proteins (by giving animals human genes, for example). This review, however, focuses not on pharmaceutical biotechnology’s methods but on its products, notably recombinant pharmaceuticals.