In this first in a proposed series of workshops on regulatory issues in animal care and use, the Institute for Laboratory Animal Research (ILAR) has addressed the existing and proposed requirements for reporting pain and distress in laboratory animals. The Animal Welfare Act, administered by the Animal and Plant Health Inspection Service of the United States Department of Agriculture (USDA), mandates that pain and distress in laboratory animals be minimized. USDA is considering two policy changes with regard to this specific mandate. Firstly, since there has been no functional definition of "distress," USDA has prepared such a definition and requested feedback from the scientific community on its usefulness for regulatory and reporting requirements. The second issue concerns the pain and distress categorization scheme for reporting to USDA. Various groups and individuals have questioned the efficacy of the current categories, and specific changes have been proposed by the Humane Society of the United States. USDA is considering these and other potential changes to the existing scheme. Thus, given these potential changes to animal welfare policy, the aim of the ILAR/NIH joint workshop was to provide feedback to the USDA. The speakers were asked to address these two issues as well as to comment upon whether the information contained in the 1992 ILAR report Recognition and Alleviation of Pain and Distress in Laboratory Animals is still useful to investigators in assisting them to comply with regulations. The speakers provided perspectives based on their individual expertise in the areas of science of pain and distress, animal welfare policy, protocol review, and/or as representatives of relevant organizations or institutions. The following proceedings are an edited transcript of their presentations.