This document has been written in response to meetings on “Locus-specific Mutation Databases” held on March 24, 1996 in Heidelberg, Germany and “Mutation Databases” on October 29, 1996 in San Francisco, California. As a chairperson of the Nomenclature committee, the first author had accepted the task of preparing and circulating a document with recommendations for debate, further discussions and most importantly for final approval/acceptance at the October 1996 meeting in San Francisco. Four drafts of this document (August 5, 1996, September 5, 1996, November 29, 1996, and May 29, 1997) were distributed to a number of investigators, the majority of whom were co-authors in the Beaudet et al, 1996 and Beutler et al, 1996 papers. This document contains modifications according to their suggestions, opinions and criticisms. Furthermore, many colleagues had offered suggestions, criticisms, and ideas through electronic communication. During the October 1996 meeting in San Francisco, there was a sufficient discussion of these recommendations and it was agreed that another, further modified draft of the document would be posted on the “World Wide Web” for final debate for a period of several weeks. This present document is also the result of all of these discussions and was approved during that October 27, 1997 meeting in Baltimore. Two manuscripts were recently published in “Human Mutation” that contain mutation nomenclature recommendations (Beaudet et al., 1996 and Beutler et al., 1996). These documents present the views of the authors after discussions during the October 19, 1994, Montreal, and the October 24-25, 1995 Minneapolis meetings. Other previously published papers/letters on nomenclature issues include the following: Beaudet & Tsui, 1993; Beutler, 1993; Antonarakis & McKusick, 1994.