The title of this volume, Plant Biotechnology: Nell Products and Applications, may look a little out of place among previous vol­ umes of Current Topics in Microbiology and Immunology that have focused mostly on issues related to human health and ani­ mal biology, However, plant biology has always been of immense and has enjoyed an intimate relationship practical importance, with medicine and other biological sciences for centuries, In­ creasing scientific specialization and the dramatic advances in the medical and chemical sciences during this century have left many persons with the impression that plant biology and plant bio­ technology is important only in relation to the agricultural sci­ ences, This is no longer true. Within the past year a genetically engineered plant virus has been used to vaccinate and protect against an animal disease (see the chapter by Lomonossoff and Hamilton), the first human trials of a potential transgenic plant­ based oral vaccine against cholera have been conducted (see the chapter by Richter and Kipp), and the first human trial of an injectable transgenic plant-derived therapeutic protein is under way (discussed in the chapter by Russell et al. ). Today plant biotechnology is being used in new and creative ways to produce therapeutic products for medicine and plastics for industry as well as new disease-and stress-resistant crops for agriculture.