The study group spent one week in Sweden and three days in Finland meeting with scientists, engineers, and public officials who have been actively working on the mercury problem in those countries. The report summarizes the findings and sets forth recommendations relating to major steps which should be taken in the U.S. to define and correct the mercury problem. Medical implications of ingestion of mercury, microbial transformation of mercury, sources, distribution, and control, ecological effects of methyl-mercury contamination, forming-food-forestry, airborne mercury, and the chemical analyses of mercury are all discussed at length. Portions of this document are not fully legible.