The Gordon Research Conference on the Biology of Spirochetes is devoted to discussions on basic research of all medically important and biologically relevant spirochetes, a unique group of Eubacteria. Many spirochetes are pathogens and cause a variety of diseases, including syphilis, Lyme disease, relapsing fever, leptospirosis, periodontal disease, digital dermatitis of cattle, and swine and human dysentery. Certain nonpathogenic spirochetes are also of great interest, such as the termite gut symbionts. The goal of this GRC is to provide a forum for exchange of ideas among groups working on different spirochetes, particularly in the area of new techniques for genetic manipulation. The application of genetic advancements and the availability of genomic sequences for Borrelia burgdorferi, B. garinii, Treponema pallidum, T. denticola, Leptospira spp. and other spirochetes are providing a wealth of new information. Combined, these data are being integrated into ongoing studies on the physiology, structure, pathogenesis, and immunobiology of these bacteria.