Gene therapy is being studied for the treatment of a wide variety of acquired and inherited disorders. Retroviruses, adenoviruses, poxviruses, adeno-associated virus, herpesviruses, and others are being engineered to serve as gene therapy vectors and are being administered to patients in a clinical setting. Infection control professionals will be asked to evaluate the use and safety of these agents in their clinics and hospitals. This review summarizes key aspects of the biotechnology and the vectors involved in gene therapy and makes recommendations for infection control.