About this report. In fulfillment of its legislative mandate to update existing toxicological profiles, the Agency for Toxic Subtances and Disease Registry (ATSDR) released an updated version of the Toxicological Profile for Mercury in April of this year (1999). As part of an extensive peer review process to ensure the scientific merit and credibility of this profile, ATSDR assembled a panel of experts in environmental health, mercury, and health risk assessment in Atlanta, Georgia on July 20 and 21, 1998 to review the draft version of the Mercury Profile developed following the Public Comment Period which lasted from October 17, 1997 to February 17, 1998. During the two-day meeting, this panel, which included key investigators from the Iraqi, Seychelles, and Faroes Islands studies, as well as representatives from other federal partner agencies and the academic and private sectors, conducted open, free-ranging discussion concerning the various aspects of mercury toxicity and the interpretation of the large data base available for mercury and its compounds. ATSDR's proposed responses to public comments was also a significant focus of discussion. The following is a summary report of the proceedings of that meeting. The contributions of the expert panel were instrumental in ensuring the quality of the final profile, and are gratefully acknowledged.