During the past several years, the terms genetic engineering, recombinant DNA research, and recombinant DNA technology have been the focus of considerable attention. Early on, molecular cloning was an emotionally charged issue that evoked heated dialogue among scientists, clinicians, and the general public. The majority of the controversy has now been set aside, and what has emerged is a series of highly innovative and highly sophisticated applications. Though less than a decade from its inception, genetic engineering is making a major impact on science, medicine, technology, and society, providing numerous opportunities for improvement of the quality of human existence. In broad terms, applications of recombinant DNA technology can be divided into four areas: biomedical, basic biological, agricultural, and industrial. Biomedical applications include the elucidation of the cellular and molecular bases of a broad spectrum of diseases, as well as in clinical medicine where both diagnostic and therapeutic applications are being